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NOTIZIARIO Neutroni e Luce di Sincrotrone Rivista del Consiglio Nazionale delle Ricerche

SOMMARIO

Cover photo: Vivaldi - vitamin B12

EDITORIALE

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C. Andreani

RASSEGNA SCIENTIFICA Interaction of Carbon Nanotubes with Adsorbates Studied by High Resolution Photoemission Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 R. Larciprete et al. Il

NOTIZIARIO Neutroni e Luce di Sincrotrone

Polymer Electrolytes Dynamics as Probed by QENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

è pubblicato a

cura del C.N.R. in collaborazione con la Facoltà di Scienze M.F.N. e il Dipartimento di Fisica dell’Università degli Studi di Roma “Tor Vergata”.

F. Aliotta and A. Triolo

The Development of Instrumentation at the ILL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Vol. 8 n. 1 Febbraio 2003 Autorizzazione del Tribunale di Roma n. 124/96 del 22-03-96

C.J. Carlile

DIRETTORE RESPONSABILE:

C. Andreani

PROGETTO E.S.S. The ESS maintains Momentum and enters the Decision Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

COMITATO DI DIREZIONE:

M. Apice, P. Bosi COMITATO DI REDAZIONE:

F. Carsughi

L. Avaldi, F. Aliotta, F. Carsughi, G. Ruocco. SEGRETERIA DI REDAZIONE:

D. Catena HANNO COLLABORATO

VARIE

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CALENDARIO

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33

SCADENZE

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FACILITIES

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A QUESTO NUMERO:

G. Cicognani, P. Cuccari GRAFICA E STAMPA:

om grafica via Fabrizio Luscino 73 00174 Roma Finito di stampare nel mese di Febbraio 2003 PER NUMERI ARRETRATI:

Paola Bosi, Tel: +39 6 49932057 Fax: +39 6 49932456 E-mail: p.bosi@dcas.cnr.it. PER INFORMAZIONI EDITORIALI:

Desy Catena, Università degli Studi di Roma “Tor Vergata”, Presidenza Facoltà di Scienze M.F.N., via della Ricerca Scientifica, 1 00133 Roma Tel: +39 6 72594100 Fax: +39 6 2023507 E-mail: desy.catena@uniroma2.it

Vol. 8 n. 1 Febbraio 2003


EDITORIALE

I

dieci anni (http://www.ill.fr/pages/menu_g/news/

O

press_release_4_%20decembre.pdf). Colin Carlile, attuale

von Laue-Paul Langevin (ILL) in Grenoble (F) for ten years

direttore dell’ILL illustra, in un articolo pubblicato in

(http://www.ill.fr/pages/menu_g/news/press_release_4_

questo numero, l’attività di ricerca e lo sviluppo di

%20decembre.pdf). The future research activities at ILL and

strumentazione prevista all’ILL nel prossimo futuro

the development on instrumentation is illustrated, in this

(http://www.ill.fr/pages/menu_g/docs/millennium_prog

issue, in an article by Colin Carlile, present ILL Director,

ramme.pdf). Altri due articoli in questo numero

illustrating the instrumentation for neutron research,

riguardano, rispettivamente, lo studio dell’interazione di

presently available at the ILL and the future of the ILL

nanotubi di carbonio con O2/NO2, effettuato ad ELETTRA

Millennium Programme

utilizzando la tecnica di spettroscopia di fotoemissione ad

(http://www.ill.fr/pages/menu_g/docs/millennium_prog

alta risoluzione, e lo studio della dinamica di polimeri

ramme.pdf). Other two articles are, respectively, about the

elettroliti.

study of the interaction of single wall nanotubes with gas

Su iniziativa del Commissario Busquin, e al fine di

phase molecule, i.e. O2/NO2, performed at ELETTRA by

promuovere in Europa una più coerente politica scientifica

high resolution photoemission spectroscopy, and of the

nel settore delle infrastrutture di ricerca, i rappresentanti

dynamics of polymer electrolytes.

dei quindici stati membri hanno istituito uno specifico

On the initiative of Commissioner Busquin, and in order to

Forum di consultazione. I componenti di questo organismo

promote a coherent European science policy on research

denominato “European Strategy Forum on Research

infrastructures the 15 member states have recently

Infrastructures” (ESFRI) si riuniranno a scadenza periodica

launched the “European Strategy Forum on Research

per discutere di grandi infrastrutture di ricerca per le

infrastructures” (ESFRI). It is expected that the Forum will

scienze naturali e non solo

endeavour to meet this requirement. Components of this

(http://www.cordis.lu/rtd2002/era-

Forum will meet regularly to discuss about needs in Europe

developments/infrastructures.htm).

about this matter (http://www.cordis.lu/rtd2002/era-

Vorrei concludere questo Editoriale ringraziando, anche a

developments/infrastructures.htm).

nome di tutta la redazione, Francesco Sacchetti per il lavoro

On behalf of the whole editorial staff I would like to thank

che ha svolto in questi anni a beneficio della nostra

Francesco Sacchetti for his precious work devoted to the

comunità nella veste di coordinatore delle Commissioni

italian neutron scattering community as former chairman of

Neutroni INFM e CNR, ed inviare gli auguri di buon lavoro

the CNR and INFM Neutron Scattering Committees. I

ai coordinatori di recente nomina, Caterina Petrillo (per

would also like to welcome the new chairpersons, Caterina

INFM) e Maria Antonietta Ricci (per il CNR).

Petrillo (for INFM) and Maria Antonietta Ricci (for CNR)

l 4 Dicembre del 2002 i governi di Francia, Germania e Gran Bretagna hanno formalmente approvato l’estensione dell’accordo intergovernativo, originariamente sottoscritto nel 1971, per ulteriori

n December 4, 2002, the Governments of France, Germany and the United Kingdom agreed to an extension of the 1971 Intergovernmental Convention on the

international research institute known as the Institut Max

and wish them a productive period of work.

Carla Andreani

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RASSEGNA SCIENTIFICA Articolo ricevuto in redazione nel mese di Ottobre 2002

INTERACTION OF CARBON NANOTUBES WITH ADSORBATES STUDIED BY HIGH RESOLUTION PHOTOEMISSION SPECTROSCOPY R. Larciprete1,2, A. Goldoni1,3, S. Lizzit1, L. Petaccia1, A. Laurita4 1 Sincrotrone Trieste, S.S. 14, Km.163,5, 34012 Basovizza (TS)- Italy 2 CNR-IMIP, Zona Industriale - 85050 - Tito Scalo (PZ) Italy

3 Laboratorio Nazionale TASC-INFM, , S.S. 14, Km.163,5, 34012 Basovizza (TS)- Italy 4 Centro di Servizi Interdipartimentale di Microscopia, UniversitĂ degli Studi della Basilicata, Potenza - Italy

Abstract We have used high-resolution photoemission spectroscopy to study the interaction of single wall nanotubes with gas phase molecules as O2 and NO2. The first aim of our investigation was to state the purity of commercial nanotubes, in the form of a bucky paper, and to follow the removal of the contaminants (Na, S, Si, Ni) present in the sample by annealing at increasing temperatures. Rapid annealing treatments of a few minutes up to 1800 K determined Ni evaporation and elimination of Na only from the near surface layer, whereas an Na-free clean sample could be obtained only after a prolonged annealing of a couple of hours at 1250 K. We have compared the interaction between the single wall nanotubes and O2 for the Na-contaminated and clean bucky paper. In the first case the adsorption was strongly altered by the Na traces, which simulated an intense sample oxidation leading to a modification of the electronic properties of the nanotubes. On the contrary, for clean single wall nanotubes, the lack of oxygen detection and the inertness of the C1s core level to large O2 doses demonstrated the absence of any chemical interaction between nanotubes and O2, up to pressures of the order of 10-6 mbar and temperatures between 150 and 300 K. Instead, a significant charge transfer was observed for NO2 adsorption. In this case the hole doping induced in the tubes by the adsorbed molecules led to a dramatic change in the C1s line shape and energy position, which corresponds macroscopically to a decrease of the resistance of the bucky paper sample.

its equator and lengthened by introducing further C hexagons. Microscopically a NT consists of one (singlewall nanotube, SWNT) or more (multi-wall nanotube, MWNT) graphene sheets, rolled-up to form coaxial cylinders, separated by approximately the intralayer distance of graphite (0.34 nm). In the latter case, the layers can be as many as fifty. In the rolled-up graphene layers the carbon lattice remains continuous around the circumference and the atoms nearly maintain the sp2 hybridization of graphite (obviously the degree of sp2 hybridization depends on the diameter of the nanotube, i.e. the curvature of the C-C bonds). The constraints imposed by the continuity of the lattice determine the formation of different chiral structure resulting from the helical twist around the tube axis. The only two types of non-helical tubes are arranged with the sides of the hexagonal carbon rings parallel or perpendicular to the axis of the tube, and are called zig-zag or armchair, respectively [1-4]. Depending on their diameter and chirality SWNTs can behave as semiconductors or metals [1,5,6] and from the transport point of view are described as the realization of one dimensional quantum objects. Therefore, SWNTs appear promising candidates for nano-scaled electronic devices or quantum wires. Moreover, the interest for NTs is increased by the evidence that their electronic structure can be easily tuned by distortion, introducing defects and functionalization of the tips and/or sidewalls with foreign atoms. In addition to these unique electronic characteristics, NTs exhibit excellent mechanical properties as they can be buckled without breaking and, on the basis of their very low weight and very high elastic modulus, are predicted to be the strongest fiber which can be fabricated, ideal to reinforce polymer and composites materials. Moreover the NT nanocapillarity properties, resulting from the large specific surface and hollow geometry, make them prime materials for gas and energy storage. The characteristics of adsorbing easily gas phase molecules can be also exploited to use NTs as high sensitive

1. Carbon nanotubes and their properties Carbon nanotubes (NTs) [1-2] are fullerene-related structures, consisting of long, thin, hollow cylinders of carbon, discovered in 1991 by S. Iijima [3,4]. These cylindrical molecules can have diameter as little as 1 nm and a length of many microns and can be visualized as an extended fullerene, where the C60 molecule has been cut at

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chemical sensors for gas molecule detection [7-12]. In this respect it was believed that the electronic characteristics of SWNTs are relatively insensitive to gas exposure, because the strong on-tube C-C sp 2 bonding should weaken the interaction between the gas molecule and carbon atoms. On the contrary, recently it has been theoretically [8-10] and experimentally [11-12] demonstrated that exposure to molecules as O2, NO2, NH3, can affect significantly the electronic and transport SWNT properties. It has been shown [11] that isolated, apparently semiconducting tubes can assume a metallic character through room temperature exposure to oxygen and that SWNT bundles and thin films once saturated with oxygen exhibit a higher electrical conductance. In the latter case rapid reversible changes in the resistance have been observed in step with the change of the gas environment, whereas for isolated semiconducting SWNTs significant rearrangement in the density of states and shrinking of the apparent band gap have been detected upon exposure to oxygen [11]. Similarly, dramatic electrical resistance variations have been measured in semiconducting SWNTs exposed to NO2 and NH3 [12], which appear extremely relevant in view of the realisation of nanotube molecular sensors. In spite of the mentioned potential of SWNTs in gas sensing, there is a delicate and crucial point that often is neglected or at least not sufficiently taken into account. This is the pureness of the samples used in the experiments aimed to state the NT capability of interacting with molecular adsorbates and being sensitive to the environment in which they are immersed. As it is described in the following, the extensive chemical processing to which SWNTs undergo during the purification procedure might leave contaminant traces hidden among the tubes or buried within the bundles. These contaminants can heavily alter the response of the NT systems to external probes, and mimic false and misleading behaviours. We have used high-resolution photoemission spectroscopy with synchrotron radiation to study the interaction at 150 K between molecular adsorbates and SWNTs in the form of commercial bucky paper. Due to chemical treatments performed on the raw nanotube material to produce the bucky paper, the sample showed traces of sodium and other contaminants, even after annealing in ultra high vacuum (UHV) for a few minutes at 1800 K or for much longer times at about 1000 K. Complete Na removal, was obtained only after a prolonged heating of a couple of hours to 1250 K. It is worth stressing that most of the experimental studies reported in the literature regarding the investigation of the electronic properties of SWNTs and their interaction with adsorbates are performed on sample which are

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degassed in UHV at temperatures of the order of 1000 1200 K. Normally the purity of the sample is not checked by any means. Our results show that standard commercial purified SWNT samples, once annealed at these temperatures still contain sizable quantity of contaminants that can interfere with the adsorbates. In the case of the Na-contaminated sample, we observed an intense interaction between SWNTs and molecular oxygen due to the charnge transfer from the tube to the Na-O complex [13-15]. On the contrary no oxygen physisorption was found when dosing the Na-free sample. Instead, a clear and strong interaction was observed when the clean SWNTS were dosed with NO,

Fig. 1. Sequence of treatments used to purify and process SWNTs. In general the “as produced” material, besides tubes, contains other carbon material (residuals of the graphite target, amorphous carbon, fullerens, onions) and metal catalyst particles (Fe, Ni, Co), which remain trapped within the bundles. The material is treated in medium and strong oxidizing acid baths to burn out the amorphous part (stage I) and dissolve the metal particles (stage II). Then is dispersed in surfactant solution to entangle the tubes. The extensive use of chemicals can leave traces of contaminants, which are difficult to detect and remove

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NO2 and NH3, in agreement with the results reported in Ref.[12]. The reproducibility and reversibility of the response of SWNTs to nitrogen oxides and ammonia adsorption undoubtedly foresee applications in the field of gas sensing. On the other hand the results observed in the case of oxygen, demonstrate the importance of a careful determination of the chemical purity of SWNT samples, as the presence of unrevealed species adsorbed on the tube walls can lead to apparent electronic properties different from the NT intrinsic ones.

2. From the row nanotube material to the free-standing bucky paper SWNTs are produced by several techniques as arc discharge, [16-17], laser ablation [18], chemical vapour deposition from hydrocarbon precursors [19], annealing of carbon nano-particles [20]. In reality, for nearly all growth methods the “as produced” material only in part consists of tubes and for the rest contains carbon material other than NTs, that is residuals of the graphite target, amorphous carbon and organised forms of carbons as fullerens and onions. Furthermore, metal catalyst particles (Fe, Ni, Co) remain trapped within the NT bundles. Before being suitable for any further use the “as produced” material has to be purified [21-23]. As it is sketched in Fig.1, the purification sequence usually starts with treatments in medium or strong acid baths (H2SO4, HNO3) to induce oxidative processes that remove the amorphous carbon part, but also to attack the weakest sites in the NTs, causing cap opening. Prolonged and/or repeated baths can also dissolve the metal particles and outcome an ensemble of entangled tubes, which are still unfeasible for the fabrication of a free-standing and compact sample. For further handling and manipulation NTs are dispersed in surfactant solutions, which disentangle the tubes. To this aim one of the most widely used compounds is sodium lauryl sulphate (C10H21NaO4S, SLS) a surfactant that absorbs at the surface of the NT bundles producing an efficient coating and inducing electrostatic repulsions able to counterbalance the van der Waal interactions and to allow NTs to be homogeneously dispersed in the solution. After filtration through micropore membranes the NT material is dried in a mat, the so-called bucky paper, which is a freestanding, easy to handle assembly of NTs, which can be manipulated and used for experiments as a normal bulky sample. Unfortunately, in spite of accurate protocols for chemicals elimination, traces of acids and surfactants can remain in the material adsorbed on the tube walls or trapped within the bundles and their presence can heavily interfere with the NT properties and simulate exotic and unpredictable behaviors [24].

2.1 Bucky paper characterization by SEM microscopy The bucky paper used in our experiment was a commercial sample (purity > 90% vol.) made of single-wall nanotubes grown by laser ablation with an average diameter of 1.4 nm. According to the producer, the SWNTs after purification were dispersed in SLS. The microscopy analysis of the sample was performed by using XL30 ESEM PHILIPS FEI equipped with an EDX detector for x-ray microanalysis. Fig. 2(a) shows a low resolution image of the bucky paper which appears as a compact mat. The NT bundles can be visualised by examining the edges of the sample, where they stick out from the compact material. An example is reported in Fig. 2(b), which shows assemblies of SWNTs, forming ropes with diameter of 10-20 nm. The bucky paper was examined by x-ray microanalysis. Fig. 3 shows the X-ray emission spectra taken in the two points marked by the arrows and attests the presence of chemical elements other than C, that is O, Ni, Na, Si, S and Ca inhomogeneously dispersed in the sample. Calibration of the upper spectrum reported in Fig. 3 estimated atomic concentrations of 83% for C, 11% for O, 6% for Si, 2% for Ni and below 1% for Na, Ca and S. The chemi-

Fig. 2. SEM images of a commercial NT bucky-paper. (a) Low resolution image showing the compact mat; (b) NT bundles sticking out from the edge of the sample.

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Fig. 3. EDAX X-ray microanalysis of a commercial nanotube bucky paper with stated purity >90% vol. The EDAX spectra measured in two different points (see arrows) of the SEM image illustrate the presence of lateral inhomogeneous distribution of the chemical contamination in the sample. For the upper spectrum the estimated atomic concentrations are 83% for C, 11% for O, 6% for Si, 2% for Ni and below 1% for Na, Ca and S.

Fig. 4. Lateral distribution of contaminants in the nanotube bucky paper (see Fig.3) obtained by x-ray microanalysis. The chemical maps are measured on the SiKa (1740 eV), NiKa (7478 eV) SKa (2307 eV) and NaKa (1041 eV) x-ray emission peaks, in the sample area shown in the 26 ¥20 mm2 SEM image reported at the top of the figure.

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Fig. 5. Survey XPS spectrum taken at 400 eV bbucky paper before any thermal treatment. The red curve in the inset shows the spectrum measured in the low binding energy region with a photon energy of 135 eV.

Fig. 6. (a) Valence band and (b) O1s core level spectra measured on the bucky paper before any thermal treatment (upper curves) and after rapid annealings at increasing temperatures up to 1800 K.

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cal maps taken in correspondence of the SiKa (1740 eV), NiKa (7478 eV) SKa (2307 eV) and NaKa (1041 eV) peaks, reported in Fig. 4 visualize the lateral distribution of contaminants in the bucky paper. To enhance the effect, the site for this analysis was properly chosen among the most contaminated in the sample. The morphology imagined in the upper figure shows the presence of contaminating fragments, which according to the SiKa map, turned out to be made of glass. Such SiO2 microsized particles, probably deriving from ultrasonication treatments in glass beakers during NT purification, are also the source of O and Ca contamination. A different distribution in the sample is observed for Ni, whose map shows an inverted contrast with respect to Si, attesting the localisation of the Ni catalyst particles only in the SWNTs. Na is detected inside the glass particles (sodium is commonly present in glass), but it is also located outside them, which demonstrates that Na contamination resides in the NT bundles as well. As for S, a clear contrast in the map is hindered by the low concentration

Fig. 7. (a) Photoemission spectra taken at photon energy of 500 eV on SWNTs treated with rapid annealing at 1700 (blue curves) and 1800 K (red curves) and (b) corresponding spectra taken in the Fermi level region at photon energy of 135 eV.

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of this element. However a predominant localisation in the NTs is evident, although even S is often contained in commercial glass. The presence of S and Na in the NT material has to be attributed to residuals of the chemicals used during purification, with a particular reference to SLS. Removal of the observed contamination was indispensable before studying the interaction of nanotubes with adsorbates. Our approach was to remove the contami-

Fig. 8. (a) Valence band, (b) C-K edge XAS and (c) C 1s core level spectra measured on the clean single-wall nanotubes.

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nants by annealing the bucky paper to increasing temperatures up to 1800 K while monitoring the chemical state of the sample by high-resolution photoemission spectroscopy.

3.The interaction of nanotubes with adsorbated studied by high resolution photoemission spectroscopy 3.1 Experimental A 1x1 cm2 piece of bucky paper was introduced into the experimental chamber (base pressure 8x10-11 mbar) of the Superesca beamline [25] at the ELETTRA (Trieste, Italy) synchrotron radiation facility and examined by high-resolution photoemission spectroscopy. The photo-electrons were collected with a homemade double-pass hemispherical analyzer (150 mm mean radius for each hemisphere), equipped with a 96-channel detector [26]. O1s, C1s and Na2p core level spectra were measured at, photon energy of 650, 400 and 135 eV, respectively, with a corresponding overall energy resolution of 200, 100 and 60 meV. The valence band (VB) spectra were measured at photon energy of 135 eV and overall energy resolu-

Fig. 9. O1s (a) and C1s (b) core level spectra measured on the clean SWNTs before and after exposure to 100 KL of O2 at 150 K.

tion of 60 meV. The analyzer acceptance angle was ± 2°. Measurements were performed with the beam impinging at normal incidence and photoelectrons were collected at emission angle of 40°. X-ray absorption spectroscopy (XAS) spectra were measured across the C1s threshold collecting the total electron yield with a channeltron. The overall energy resolution of the XAS measurements was 35 meV. Photoemission and XAS spectra were taken before any thermal treatment and after annealing cycles up to 1800 K. The sample was heated resistively and the temperature was measured by a calibrated pyrometer, with an uncertainty of ± 30 K. For gas adsorption the bucky paper was cooled to 150 K and molecular oxygen and nitrogen dioxide were admitted to the chamber through a leak valve. The exposure was evaluated using uncorrected ionization gauge readings, which were integrated to obtain the dose in Langmuir (1L=1x106 Torrs). 3.2 SWNTs cleaning by thermal annealing. Fig. 5 shows the XPS survey spectrum taken on the “as received” bucky paper at photon energy of 600 eV, which shows only the intense C1s at 284 eV. The presence of Na in the sample is revealed when changing the photon energy to 135 eV, which makes the Na2p peak clearly evident at 32 eV. Moreover the weak O2s core level appears

Fig. 10. C1s spectra (dots) measured on the Na-contaminated SWNTs after thermal annealing (bottom) and after exposure to 100 KL of O2 (top) at 150 K. The best-fit curves and peak components are also shown.

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at 26 eV, close to the valence band, which extends up to the Fermi level. A first approach to obtain Na desorption consisted in treating the bucky paper with rapid annealings (a few minutes) at increasing temperature up to 1800 K. The sequence of VB spectra reported in Fig. 6 illustrates how the progressive heating removes Na and reveals the real

face layer, but did not allow the bulk Na to be eliminated. Subsequent exposure to the x-ray beam induced the diffusion of the sodium still present in the deep layers of the sample, which progressively segregated at the surface. Complete Na removal could be obtained only after keeping the bucky paper at 1250 K for a couple of hours. Besides Na other contaminants were present in the

Fig. 12. Sequence of C1s spectra taken by fast photoemission on SWNTs during the exposure to 230 L of NO2 at 150 L.

SWNT sample. Fig. 7 compares the XPS spectra measured on the bucky paper treated with rapid annealing at 1700 K (blue curve) and 1800 K (red curve). The blue curve in Fig. 7(a) shows the Ni3p, Si2p and S2p peaks at

Fig. 11. (a) C1s and (b) O1s core level spectra measured on the clean SWNTs before and after exposure to 100 KL of O2 at 150 K.

features of the nanotube VB [27]. The simultaneous oxygen desorption, indicated by the disappearing of the O2s feature, is better illustrated by the sequence of O1s spectra reported in Fig. 6. The integrity of the tubes in the bucky paper after the repeated annealing cycles was checked in situ by electron energy loss spectroscopy and ex situ by Raman spectroscopy. In both cases no variation from the spectra measured on the un-annealed sample was observed, which confirmed the absence of measurable damaging as amorphization, merging into multiwall structures or tube collapse induced by the thermal treatment. The sequence of rapid annealing to high temperature determined a satisfactory removal of Na from the near sur-

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Fig. 13. NO2 dose (red) and bucky paper resistance (bleu) vs. time measured during the NO2 up take on SWNTs.

about 72, 110 and 170 eV, respectively. For Si2p, the ~10 eV shift in BE with respect to pure Si is due to local charging effects in the glass fragments. Moreover the change in the Si2p and S2p line shapes observed after different thermal treatments can be attributes to dissoci-

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ation processes and reactions thermally induced in the contaminating species. The red curve in Fig. 7(a) demonstrates that a rapid annealing at 1800 K was successful in evaporating Ni. The comparison between the bleu and the red curves shows that metal elimination corresponds to a clear decrease of the emission at the Fermi level, which can be already appreciated in the survey XPS spectra taken at 500 eV, but is much more evident in the spectra measured at 135 eV. Si and S could not be eliminated by any treatment of the sample compatible with a reasonable tube integrity. However by using spectromicroscopy performed with a 100 nm x-ray nanoprobe [28] we achieved the demonstration that these elements were distributed in the bucky paper as localised spots (likely residuals of the glass fragments), which occupy less than 10 % of the total sample area. The absence of any influence of such contaminants on the electronic properties of the tube was demonstrated by the perfect overlapping between the C1s line shape measured by spectromicroscopy in a contaminantfree point [28] and the peak measured using the conventional x-ray beam, which integrates over a 100x10 mm2 area. This SWNT sample was then considered clean. 3.3 Characterization of the clean SWNTs Fig. 8 shows the valence band, C1s core level and C Kedge absorption spectra taken on the clean bucky paper sample, which can be taken as reference spectra for SWNTs. The VB spectra reported in Fig8(a) shows the characteristic features of graphite resulting from the sp2 hybridization of the C atoms, that is the peak at 3.5 eV assigned to 2p-p states, the bands at 5.5 and 8 eV, which share a dominant 2p-s character, and the bands at 13.6 eV and around 17 eV, attributed to mixed 2s-2p hybridized states and to 2s states, respectively [27,29,30] Similarly, the XAS spectrum of the SWNTs shown in Fig. 8(b) exhibits the typical graphite features, which are the sharp 1s→π∗ peak at 285.5 eV, that is a fingerprint of sp2 hybridized C atoms and by the structured lineshape of the 1s→σ∗ edge at 291.4 eV. The feature at 288 eV in the single-wall NTs spectrum has been assigned to interlayer bands with s symmetry [31] The C1s core level measured on the clean SWNTs is shown in Fig. 8(c). This spectrum was best-fitted with Doniach-Sunich functions convoluted with Gaussians into two components, C1 at 284.41 ± 0.02 and C2 at 284.57 ± 0.02 eV with a relative intensity IC2/IC1 of 0.85. Following the results described above this splitting cannot be attributed to the presence of contaminants. On the other hand the constancy of the IC2/IC1 ratio after several annealing cycles above 1450 K, which are known to heal structural defects of the NT walls [21], excludes also the attribution of one component to C atoms surrounding lattice defects or carrying dangling bonds. Then the two

C1s components are attributed to tubes with metallic and semiconducting properties, which are both contained in the bucky paper. As for the relative intensity IC2/IC1~ 0.8 it is worth noting that, according to the dispersion relations for small diameter SWNTs, all armchairs tubes and 1/3 of possible zigzag and chiral tubes are metallic while the other are semiconducting [5]. However, in a real sample the metallic to semiconducting ratio might be strongly altered as the diameter (and the chirality) distribution of the tubes depends on the growth parameters [32-33]. 3.4 Adsorbtion of molecular oxygen on SWNTs As it was stressed in the introduction the sensitivity of SWNTs to adsorbed gases is extremely important in view of applications of these nanostructures to gas sensing and gas storage. Among other molecules, oxygen is a special candidate to test the possibility of SWNT gas sensing, as it has been observed a strong change in the conductivity and density of states of isolated SWNTs when the surrounding environment was cycled between oxygen (or air) and vacuum [11]. This effect was measured for semiconducting tubes and the conclusion was that these tubes acquire the characteristics of metallic ones, whereas no effect has been observed for metallic tubes. We have exposed to oxygen the bucky paper which contained traces of Na [24]. Oxygen exposure was performed at 150 K. Fig. 9(a) and 9(b) show the O1s and C1s core levels measured by fast XPS during the up-take. The dark brown curves correspond to the undosed sample at the beginning of the up-take. The occurrence of oxygen chemisorption on the tubes is attested by the appearing of the O1s peak at 532 eV, which progressively rises with increasing O2 dose. Correspondingly the sequence of the C1s spectra in Fig. 9(b) shows a progressive shift towards lower BE and a line shape modification. These behaviors attest the presence of a significant interaction between NTs and adsorbed oxygen. Quantitative indications on the modification of the C1s core level are obtained by analyzing the spectra measured before and after exposure to O2 and reported in Fig. 10. In the first case the C1 and C2 components appear at 284.72 ± 0.02 eV and 284.43 ± 0.02 eV respectively, with an energy separation ∆E = 0.29± 0.04 eV. After an O2 dose of 100 KL, C1 and C2 shift to 284.30 ± 0.02 eV and 284.17± 0.02 eV, with (∆E= 0.13 ± 0.04 eV [24]). Fig. 11 illustrates the corresponding results obtained when dosing with O2 the Na-free sample [24]. The clean SWNT bucky paper was exposed to 10 KL of molecular oxygen at temperature of 150 K. Figures 11(a) and 11(b) compare the C1s and the O1s spectra measured in vacuum before exposure to O2 and in the presence of O2 at a pressure of 10-6 mbar, after a total dose of 10 KL of O2 The lack of any modification of the C1s line shape and

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the flatness of the O1s spectra reveal the absence of any oxygen adsorption on the tube walls, in the grooves between neighboring tubes or in the interstitial sites in the tube bundles. Furthermore, the bucky paper has been extracted from UHV, kept for a few hours in atmosphere and examined again by photoemission, but no change in the C1s and VB spectral line shape and no emission in correspondence of the O1s were observed. In the case of planar graphite oxygen adsorption is due entirely to van der Waals forces and above 50 K occurs exclusively in the presence of lattice defects. Similarly, at variance with results reported in Ref.[11], for SWNTs we did not detect any sign of electronic interaction with molecular oxygen at least for O2 pressure up to 10-6 mbar and temperature between 150 and 300 K. Our findings are in close agreement with the recent results reported by Ulbricht et al. [34], who found that below 100 K O2 binds to SWNTs as well as to graphite by van der Walls interaction and that not even this phisisorbed oxygen can influence the transport properties of the nanotubes by chemical doping. Then the C1s shift observed for the Na-contaminated sample exposed to oxygen has to be exclusively related to the charge transfer between Na and O. The Na- contaminated NTs can be assimilated to dispersed phases of alkali atoms on graphite [13-15]. For these systems, a charge donation from the electropositive adsorbed atom to graphite takes place, that, depending on the alkali concentration, can shift the C1s peak several tenths of eV towards higher BEs [14]. Upon oxygen adsorption, the interaction between Na and O redistributes the charge which is withdrawn from the SWNTs and transferred to the Na-O complex [15]. These results highlight the extreme importance of using sensitive diagnostics to state the purity of samples treated with chemical processing, especially when the aim is the investigation of the intrinsic NT properties, because even traces of reactive contaminants buried among the tube bundles can interfere with the adsorbates and originate misleading behaviours. 3.5 Adsorbtion of NO2. on SWNTs At variance with O2, an intense interaction was observed between clean SWNTs and NH3, NO and NO2. Figure 12 shows the C1s core level measured by fast XPS during the NO2 up-take on the bucky paper kept at 150 K. The spectra show a huge change in the peak line shape and energy position. Because NO 2 is a strong oxidizer a charge transfer occurs from the nanotube to the adsorbed molecules, which in the rigid band model corresponds to a down BE shift of the carbon related features. In the SWNTs, which act as p-type semiconductors, such hole doping corresponds to an increase in the conductivity. Indeed the resistance of the bucky paper sample mea-

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sured during NO 2 adsorption, which is reported in Fig.13 together with the NO2 dose as a function of time, exhibits a continuos decrease with a rate that follows the NO2 dosing rate. These results reproduce very closely the results reported in Ref.[12], for SWNTs exposed to nitrogen dioxide.

4. Conclusions Chemical processing necessary to purify SWNTs can lead to sample contamination, which is not trivial to remove. The annealing procedures usually followed to obtain “clean” SWNT samples, are not always sufficient. This is a delicate point, because when the presence of impuritiy traces is neglected, the attribution of the observed behavior to NTs could yield incorrect data interpretation. We showed that the interaction between SWNTs and molecular oxygen is strongly altered by the presence of traces of Na trapped in the bucky paper sample, which simulate an intense chemisorption of the molecule on the tube walls leading to a modification of the electronic properties of the nanotubes. However if the experiment is performed on clean SWNTs, the lack of oxygen detection and the inertness of the C1s core level to large O2 doses demonstrates the absence of any interaction between SWNTs and O2, up to pressures of the order of 10-6 mbar and temperatures between 150 and 300 K. On the contrary a significant charge transfer was observed in the case of NO2 adsorption. In this case the hole doping induced in the tubes by the presence of the adsorbed molecules leads to a dramatic change in the C1s line shape and energy position, which corresponds macroscopically to a decrease of the resistivity of the SWNT sample. The results obtained for NO2, as well as for NO and NH3 confirm that SWNTs could find use as powerful chemical sensors for toxic molecules.

Acknowledgements The authors wish to thank M. Barnaba for his indispensable technical assistance

References 1. R. Saito, G. Dresselhaus and M.S. Dresselhaus (Eds.), Physical Properties of Carbon Nanotubes, Imperial College Press, London (1998) and references therein. 2. H. Dai, Surf. Sci. 500 (2002) 218 3. S. Iijima, Nature 354 (1991) 56 4. S. Iijima, and T. Ichihashi, Nature 363 (1993) 603 5. N. Hamada, S.I. Sawada, and A. Oshiyama, Phys. Rev. Lett. 68 (1992) 1579

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6. J.W.G.Wildoer, L.C. Venema, A.G. Rinzler, R.E. Smalley, and C. Dekker Nature 391 (1998) 59 7. O. K. Varghese, P. D. Kichambre, D. Gong, K. G. Ong, E. C. Dickey, C. A. Grimes, Sens. Actuators B 81 (2001) 32 8. S.-H. Jhi, S. G. Louie and M. L. Cohen, Phys. Rev. Lett. 85 (2000) 1710 9. H. Chang, J. D. Lee, S. M. Lee and Y. H. Lee, Appl. Phys. Lett. 79 (2001) 3863 10. S. Peng and K. Cho, Nanotechnology 11 (2000) 57 11. P. G. Collins, K. Bradley, M.Ishigami and A. Zettl, Science 287 (2000) 1801 12. J. Kong, N. R. Franklin, C. Zhou, M. G. Chapline, S. Peng, K. Cho, H. Dai, Science 287 (2000) 622 13. K. M. Hock, J. C. Barnard, R. E. Palmer, H. Ishida, Phys. Rev. Lett. 71 (1993) 641 14. P. Bennich, C. Puglia, A Brühwiler, A. Nillson, A. J. Maxwell, A. Sandell and N. Mårtensson, Phys. Rev. B 59 (1999) 8292 15. C. Puglia, P. Bennich, J. Hasselström, A Brühwiler, A. Nillson, A. J. Maxwell, N. Mårtensson, P. Rudolf, Surf. Science 383 (1997) 149 16. D.S. Bethune, C.H. Kiang, M. DeVries, G. Gorman, R.Savoy, J. Vazquez, R. Beyers, Nature 363 (1993) 605 17. C. Journet, W. Maser, P. Bernier, A. Loiseau, M.Delachapelle, S. Lefrant, P. Deniard, R. Lee, J. Fischer, Nature 388 (1997) 756 18. A. Thess, R. Lee, P. Nikolaev, H. Dai, P. Petit, J. Robert, C. Xu, Y. Lee, S. Kim, A. Rinzler, D. Colbert, G.Scuseria, D. Tomanek, J. Fischer, R. Smalley, Science 273 (1996)483 19. J. Kong, H. Soh, A. Cassell, C.F. Quate, H. Dai, Nature 395 (1998) 878.

20. S. Botti, R. Ciardi, M.L. Terranova, S. Piccirillo, V. Sessa, M. Rossi, and M. Vittori-Antisari, Appl. Phys. Lett. 80 (2002) 1441 21. M. Monthioux, B. W. Smith, B. Burteaux, A. Claye, J. E. Fisher, D. E. Luzzi, Carbon, 39 (2001) 1251 22. I. W. Chiang, B. E. Brinson. R. E. Smalley, J. L. Margrave and R. H Hauge, J. Phys. Chem. B 105 (2001) 1157 23. M. Moon, K. H. An, Y. H. Lee, Y. S. Park, D. J. Bae, G.-S. Park, J. Phys. Chem. B 105 (2001) 5677 24. R. Larciprete, A. Goldoni, S. Lizzit, in press in Nucl. Instr. Meth. B 25. A. Abrami et al., Rev. Sci. Instrum. 66 (1995) 1618 26. L. Gori, R. Tommasini, G. Cautero, D. Giuressi, M. Barnaba, A. Accardo, S. Carrabo, G. Paolucci, Nucl. Instr. Meth. Phys. Res. A 431 (1999) 338. 27. R. Larciprete, S. Lizzit, S. Botti, C. Cepek and A. Goldoni, Phys. Rev. B 66 (2002) R 28. R. Larciprete, et al. unpublished result 29. F.R. McFeely, S.P. Kowalczyk, L. Ley, R.G. Cavell, R.A. Pollak, and D.A. Shirley, Phys. Rev. B 9, (1974) 5268 30. A. Bianconi, S.B.M. Hagstro¨m, and R.Z. Bachrach, Phys. Rev. B 16 (1977) 5543 31. S . Imamura, H. Shimada, H. Matsubayashi, M. Yumura, K. Uchida, S. Oshima, Y. Kuriki, Y. Yoshimura, T. Sato, and A. Nishijima, Physica B 208 (1995) 541 32. Bandow, Phys. Rev. Lett. 80 (1998) 5003 33. A. G. Rinzler et al., Appl. Phys. A 67 (1998) 29 34. H. Ulbricht, G. Moos and T. Hertel, Phys. Rev. B 66 (2002) 075404

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Articolo ricevuto in redazione nel mese di Novembre 2002

POLYMER ELECTROLYTES DYNAMICS AS PROBED BY QENS Francesco Aliotta, Alessandro Triolo Istituto per i Processi Chimico Fisici del CNR – Sezione di Messina Via La Farina 237, 98123 Messina, Italy

1. Introduction Polymer dynamics is well known to cover a large number of decades in both temporal and spatial extent [1-5]. A number of different relaxation processes can be characterized, accounting for the complex macroscopic behavior of such materials. Such complexity implies that an optimized manufacturing of polymer-based materials requires a detailed understanding of the microscopic events whose resultant is the bulk performance. Dielectric spectroscopy and viscoelastic characterizations are the most commonly applied techniques to probe the microscopic dynamics in polymers [1, 3-4]. However these techniques cover a range of frequencies which doesn’t access the fast nsec to psec range that is relevant for microscopic events. On the contrary, QENS perfectly fits in this temporal regime and provides the unique information on the spatial extent of the dynamic process (see e.g. [5]). Such points together with the high sensitivity to the hydrogen atom (whose high incoherent scattering cross section, often dominates the contribution from other chemical species) represent some of the strength of the QENS technique as compared to other complementary techniques. In fact, in the years, it became well understood that due to the complexity of polymer dynamics and to the limited temporal range accessible to each single experimental technique, only the combination of different complementary experimental approaches can provide a reliable scenario to understand polymer dynamics. In this report, we show some recent results obtained from our group in the characterization of polymer electrolytes dynamics by means of QENS, with the support of other complementary techniques. Polymer Electrolytes have attracted a great deal of academic and industrial attention, due to their potential application for a huge variety of smart applications, ranging from secondary batteries to electrochromic devices etc [6-8]. They are generally prepared by proper mixing of a polyether macromolecule with salt (both inorganic and organic) [7]. The archetypal representative of this class of materials is polyethylene oxide doped with lithium-based salts. The ether portion of the macromolecule shows a large affinity towards complexing the Li+

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cation. Accordingly, a number of characterizations evidenced the existence of solvated cations and free anions diffusing in the matrix, when dissolving a salt in PEO [710]. Such complexing between the cation and the ether units of the polymer leads to a strong crosslink effect: evidences exist that up to four ether units (either belonging to the same polymer chain or to different ones) can simultaneously coordinate the cation [11]. Such an effect drastically slows down the polymer dynamics. As a consequence of the nature of the coordination (weak chemical bonding) and of the thermal agitation, a peculiar process can lead to electric conduction in such materials: not only the anions are free to conduct the current, but also the thermal agitation may temporarily and partially disrupt the coordination of the cation, as consequence of the polymer segmental motions. The consequence of such a process is that the cation will provide a weak but sensible electric conduction, which is thermally activated (as the polymer segmental dynamics is). Such a situation is ideal for a number of practical applications: Polymer Electrolytes are characterized by the optimal mechanical performances of the polymer matrix (good consistency, film preparation, high flexibility etc) and by the good electrical performances of salt solutions [7,8]. Essentially the conduction process can be rationalized in terms of an hopping model of the cation from one coordination site to next one, such a process is directly connected to the polymer segmental relaxation [12]. The large degree of knowledge that has been obtained studying the segmental dynamics in conventional synthetic polymers with QENS, can then be efficiently applied to the characterization of Polymer Electrolytes, where this dynamics is directly connected to the conduction process. 2. The case of PEO-LiBETI PEO doped with LiBETI (BETI corresponding to N (SO2C2F5)2+(bis perfluoroetil sulfonil immide)) (PEO15-LiBETI) was investigated by means of QENS both at a backscattering spectrometer and at a Time of Flight one. The dynamic information accessible at the two instruments is strongly complementary, as the former covers

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the range between 10-11 and 10-9 sec and the latter covers between 10-13 and 10-11 sec. The IN16 (ILL) backscattering instrument was used to probe the slow dynamics with an instrumental resolution of 1 µeV (λ=6.271 ?). NEAT (BENSC, HMI) is a ToF spectrometer and was used with a wavelength of 5.1 ?, thus achieving a resolution of 93 µeV. Both the instruments covered the Q range between 0.5 and 2.0 Å-1. One of the major limitations to the use of PEO-based Polymer Electrolytes is their tendency to organise in a semi-crystalline way: the macromolecule chains tend to allign themselves in a lamellar like way, thus leading to a highly organized morphology, occasionally separated by completely amorphous regions (see e.g. [13] and references therein). As the conduction behaviour occurs primarily in the amorphous phase, it is clear that semicrystalline polymers are not ideal materials for conducting applications and so they can be used only above their melting point. In the case of salt addition to PEO, the situation becomes even more complex, as different crystalline phases can then form, as a consequence of the formation of the so called Crystalline Complex (CC). Such crystalline phases contain salt complexed by the PEO chains with a well defined stoichiometry. PEO-LiBETI is a typical example of complex semi-crystalline Polymer Electrolyte [14]. It has been found that at least two different CC can form, depending on salt content and temperature, differing in their chemical composition [14-15]. At the concentration that we probed, only two crystalline phases can coexist: pure PEO and CCI (corresponding to a composition: PEO~6Li [14]). Above ca. 60 C these phases melt and the mixture start to show interesting conducting performances. Such a behaviour (that was derived by SAXS-WAXS, DSC and conductivity measurements [15]) is confirmed by our QENS data on IN16. These are reported in Fig. 1 for the case of pure PEO and PEO15LiBETI (where the n=15 pedix means that the composition of the mixture is such that for each Li cation, 15 ether units are present in the mixture) at a selected value for the momentum transfer. A fixed energy scan is reported as a function of the temperature: the number of neutrons scattered from the sample without appreciable energy exchange is plotted versus the temperature. It is evident that only when some thermal process occurs, which increases the polymer dynamics, a sensible decrease of such a number is observed (see e.g. [16]). The curve for pure PEO directly reflects the semi-crystalline behaviour of this polymer. Deviations from an almost linear behaviour at low temperature (related to the Lamb-Mossbauer effect) can be appreciated at T>200 K. This temperature corresponds to the glass transition of the fully amorphous PEO and only at 327 K a well defined decrease of the elastically scat-

tered intensity can be observed, which is related to the melting of the crystalline portion. It is well known that the crystalline phase (which is characterized by an extremely slow dynamics itself) highly hinders the segmental dynamics of the amorphous phase coexisting in the semi crystalline materials. When the crystalline phase melts (at ca. 327 K) the amorphous phase can then relax without further hindering and turns out to be extremely fast, so that in the present instrumental configuration (instrumental resolution, ∆E=1 µeV and

Fig. 1. Fixed Energy Scan obtained for pure PEO and PEO15-LiBETI as a function of the temperature on IN16, at Q=2.16 ?-1, with a resolution ∆E=1 µeV. The two thermal transitions for pure PEO are highlighted and the experimental evidence of a slower segmental dynamics in the doped PEO is indicated.

-12 µeV <E<12 µeV), no further elastically scattered intensity can be observed and at 340 K a flat temperature dependence can be observed, that is related to the empty cell scattering. The situation is drastically different for the case of LiBETI doped PEO. Firstly, we note that the melting temperature for the crystalline phases occurs at a lower temperature (ca. 330 K). After meslting, the dynamics of the material remains slow enough to be appreciated (as opposite to pure PEO) and a progressive decreasing of the elastically scattered intensity occurs as temperature increases. This feature is directly related to the drastic slowing down effect due to the formation of transient crosslinks in the doped PEO. To further explore this behaviour, we probed the polymer dynamics with an instrument that allows to probe faster dynamics and so to observe significant signal also for PEO above its melting point [17-18]. On ToF instruments, using a wavelength λ=5.1 ?, we covered a temporal window between 0.002 and 0.3 nsec, where the melt PEO dynamics can be appreciated at temperatures between 350 and 430 K. As an example, if Fig. 2, we report a fit of the QENS data from PEO at 353 K [17]. In order

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Fig. 2. Time of Flight data from pure PEO at 353 K and Q=1.96 ?-1. Data have been modelled asuming three components: i. a fast Lorentzian, accounting for librational motions, ii. a non-Debye term, modelled with the Kohlarusch-William-Watts function and iii. an elastic term accounting for slow dynamics than accessible at the present instrumental setting. In the inset, the average relaxation time, <τ>, obtained from the QENS measurements is compared, in an Arrhenius plot, with corresponding data obtained from complementary techniques (DS: Dielectric spectroscopy [22], NMR: 13C-Nuclear Magnetic Relaxation [23], NSE: Neutron Spin Echo (data at Q=1.0 ?-1) [24]).

to describe the data, two contributions were considered: a very fast dynamic event, which appear to be temperature and Q independent, that was described with a Lorentzian function, and a much slower component related to the segmental dynamics of the polymer. The latter term was described in terms of the Fourier transform of the so called stretched exponential function: exp(t/τ∗)β, with τ∗ a characteristic time for the relaxation and β a parameter accounting for the deviation of the relaxation from a purely Debye-like one. Moreover an elastic term has also been considered, accounting for the dynamics that is unresolved at the present instrumental resolution. In the inset the relaxation map for PEO is reported as obtained by combination of data derived from a variety of experimental techniques. In the case of our QENS data, <τ>=τ∗/β Γ(1/β) (Γ being the gamma function) is reported. It can be appreciated that the QENS data provide an extension of the relaxation map for PEO to a temporal range that is not easily accessible to other experimental techniques. In Fig. 3, the QENS data from PEO15LiBETI is reported for T=160 C. The data have been interpreted in terms of a more complex model than for pure PEO. It is well known that Polymer Electrolytes with low salt content are characterised by a bimodal polymer dynamics [1921]. In the past DSC [19-20], light scattering [21] and our QENS results [17-18] supported this model. In particular, it is believed that microheterogeneities might generate

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Fig. 3. Time of Flight data form PEO15-LiBETI obtained on NEAT at 433 K and Q=1.96 ?-1. Data have been modelled assuming four different components: i. a fast Lorentzian term accounting for fast librational motions, ii. a KWW term with the same parameters as pure PEO (see data in Figure 2), iii. a KWW term accounting for the slower dynamics of the PEO-Li complexes microdomains and iv. an elastic term accounting for unresolved dynamics at the present instrumental resolution.

when dissolving limited quantities of salt in a polyether: pure PEO domains and domains where the PEO chains are involve in cation coordination can coexist and are characterised by different dynamic properties, the latter domains being characterised by a much slower dynamics. Accordingly, we modelled our data with a linear combination of a fast (lorentzian) term and two different KWW terms, characterised by different τ∗ and β. In particular, the faster process has been assumed to have the same Kohlrausch-Williams-Watts (KWW) parameters as obtained for pure PEO, that means that both the characteristic time and the stretching parameters where assumed to be equal to ones obtained for pure PEO at the same temperature (we note, by passing, that the β parameter for PEO maintained essentially constant to the value of 0.6 in the explored temperature range). The slower component corresponds to a much stretched relaxation, as indicated by the higher value for β (β =0.45); this would indicate a much higher degree of cooperativity in the relaxation and such an interpretation nicely fits with the model of transient crosslinks, interconnecting different chain portions. Work is now in progress to further support this model on the basis of extended experimental evidences. 3. The case of pPEGMA polyelectrolytes The difficulties originated by the coexistence of amorphous and crystalline phases can be overcome by using poly(ethylene glycole) methacrylate (pPEGMA), a highly branched polymer that appears promising from this point of view [25,26]. Some pPEGMA polyelctrolytes,

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Fig. 4. Temperature dependences of ln[I(Q)] for pure pPegma and for its mixtures with NH4CF3SO3 and NaCF3SO3.

obtained by the addition of different salts, have been investigated trying for a correlation between the results from internal friction and conductivity measurements [26]. It has been observed that the addition of lighter cations induce a smaller decrease of the glass transition temperature allowing to obtain materials exhibiting higher conductivities. A similar dependence of the conductivity dependence from the ion size had been previously observed in PEO based systems [28]. In the following we report about the first Incoherent Quasi-Elastic Neutron Scattering (IQENS) experiment on PEGMA-based polymer electrolytes [29], performed to investigate the correlation between the observed conductivity of the system and the local relaxation of the side groups of the polymeric chains. The polymeric matrix (pPEGMA) was synthesized starting from poly(ethylene glycol)ethyl ether methacrylate [(CH2=C(CH3)CO2(CH2H2O)nC2H5] with average Mn ~ 246 (see ref. [26] for details) and solid solutions of pPEGMA with NH4CF3SO3 and NaCF3SO3, at a 9:1 ratio of ethylene oxide repeat units (EO) for each salt molecule, have been prepared . The experiment has been performed on films, 0.1 mm thick, by the IN10 spectrometer at ILL (Grenoble), using a neutron wavelength of 6.27Å. and an instrumental resolution (HWHM) of 0.36µeV (vanadium). ). IQENS have been collected over the energy range -10µeV£E£10µeV, exploring the exchanged wave vectors from 0.5Å-1 to 1.96Å-1. An inspection of the elastic scans performed both on pure pPEGMA and in its complexes with the two salts, reported in Fig. 4, evidenciates the existence of two distinct changes of slope: one takes place at about 100K and seems to be independent on the system composition, so we can definitely assign it to some internal relaxation of

Fig. 5. Scattering profile, Q-integrated, for pure pPEGMA at 275 K. Open circles: experimental data; continuous line: fitting results with stretched exponential; dotted line: resolved quasi-elastic contribution; dasheddotted line: resolution enlarged contribution

the polymer chain; the ones located at higher temperatures could be related with the glass transitions of the samples. In effect, the temperature values, estimated by the kink positions of the Debye-Waller factor, turn out to be in excellent agreement with the Tg values deduced by the mechanical data obtained at 0.3 Hz [27], more precisely 238 K for pure PEGMA and 275 K and 288 K for its complexes with ammonium and sodium salt respectively. Then IQENS spectra have been collected for each sample, at 3 different temperatures, corresponding at the same values of the T/Tg ratios for all the three samples (T/Tg = 0.95, 1.05, 1.16). In addition, a spectrum from pure pPEGMA has been collected at T=200K, corresponding at T/Tg=0.84. The data have revealed the existence of a fast contribution, which appears almost Q independent. Also in this case a stretched exponential function was adopted as the fitting model. The data are well fitted by the adopted model with β ∼ 0.85 (±10%) for all the samples. The existence of an additional very slow translational diffusion in our systems can be deduced by the Q dependence of the intensity of the elastic line, but will require further measurements, at higher temperatures, in order to be resolved. In Fig. 5 we report, as an example, the energy spectra, integrated over the whole Q range, for pure PEGMA, at 275 K, together with the fitting results. The values of 1/τ , obtained by the fitting procedure and reported in Fig. 6 as a function of T/Tg behave almost Arrhenian with an activation energy of about 10 kJ/mol. The addition of a salt reflects in a slowing down of the observed rotational motion, in agreement with literature indications for a stiffening of the side branches of the polymers, due to the formation of complexes with the ions. However, it

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Fig. 6. T/Tg dependence of the values of 1/τ , as obtained by the fitting procedure.

should be noticed that, rescaled with respect to Tg, the orientational motion monitored by IQENS is identical both in pure PEGMA and in its complexes. The IQENS results can be correlated with the conductivity data from ref. 27, and reported in Fig. 7 as a function of T/Tg (data for the system pPEGMA+ LiCF3SO3 are included in the same figure). The occurrence that, for metal ions, the conductivity appears independent on the kind of the charge carrier, when the data are rescaled at the same reduced temperature, suggests that in this case the observed differences are mainly due to the variation of Tg induced by the salt. The stiffening of the chains, induced by the intermolecular interaction between the cation and the lone pairs of the electrons from neighboring oxygen, and the effect of the size of the cation on the chain flexibility result in the elevation of the glass transition temperature. Since the diffusion of charges is related with the segmental motion of the polymer chains, smaller cations produce smaller increasing of the glass transition temperature and, as a consequence, at a fixed temperature, pPEGMA samples with lighter ions show a higher conductivity. In the case of ammonium salt a higher charge mobility is observed. The effect could be rationalized [27] by taking into account the following kinetic equilibrium:

NH

+ 4

⇔ NH

3

+H

+

suggesting that the higher conductivity is due, at least partially, to protons.

4. Concluding remarks In the case of PEO-LiBETI, the observed reorientational relaxation process, ascribed to the conformal fluctuations of the chain segments between the cross-links

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Fig. 7. Conductivity data from ref. 27, reported as a function of T/Tg. Open circles: pPEGMA+ NH4CF3SO3; triangles: pPEGMA+ LiCF3SO3; solid circles: pPEGMA+ NaCF3SO3

formed by the cations, takes place in the nanosecond time scale. A much longer time scale is observed in the case of pPEGMA polyelectrolytes. Furthermore, the addition of the salt results in a clear change of the segmental dynamics, respect to pure polymer in the case of PEO. Such a result agrees very well with the indication of recent QENS [30] and Neutron Spin Echo [31] experiments on PEO-lithium salt complexes. In these experiments it was shown that the introduction of even small quantities of salt dramatically affects the rate and the nature of the observed relaxation in the polymer host. The situation appears very different when pPEGMA-salt complexes are taken into consideration. First of all, the observed reorientational relaxation process takes place on a much longer time scale. From one side, the difference could be imputed to the circumstance that, being PEO polymer electrolytes biphasic at room temperature, the experiments on PEO-based systems has been performed at higher temperatures. However, the situation appears quite different when the results from the elastic scans from PEO-LiBETI and pPEGMA complexes are compared (see Figs. 1 and 4). In the case of pPEGMA, the addition of salt seems to induce just a shift in the glass transition temperature while a very different behaviour is observed when PEO-systems are taken into consideration. Tentatively, the different behaviour could be ascribed to the different size of the side chains: their shorter length in the case of pPEGMA could reflects in a less efficient complexation of the cation. Additional points that should be better addressed concern with the effects of the presence of salt on the translational diffusion of the polymer chains. Further measurements at higher temperatures are actually in planning to investigate into details the effect of the addition of salt on this very slow relaxation process.

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Acknowledgements Experiments at BENSC were supported by the European Community in the framework of the program: Access to Research Infrastructure Action of the Improving Human Potential Programme (IHP), contract number HPRI-CT1999-00020. We acknowledge the experienced support by the local team (Dr. R.E. Lechner). We also acknowledge the ILL for providing the beam time and financial support to the experiments run on IN10 and IN16. The PEO-LiBETI samples were kindly provided by S. Passerini (ENEA, I). Illuminating discussions with Dr. V. Arrighi (Heriot-Watt University, UK) are also acknowledged.

References 1. J.D. Ferry, Viscoelastic Properties of Polymers, Wiley, New York, 1980 2. L.W. Jelinski, in High Resolution NMR Spectroscopy of synthetic Polymers in bulk, VHS Pubblishers (Komoroski Ed.), Deerfield Beach, FL, 1986 3. R.T. Bailey, A.M. Northand R.A. Pethrick, Molecular Motions in High Polymers, Clarendon Press, Oxford, 1981 4. N.G. McCrum, B.E. Read and G. Williams, Anelastic and Dielectric Effects in Polymeric Solids, Wiley, New York, 1967 5. J.S. Higgins and H.C. Benoit, Polymers and Neutron Scattering, Oxford University Press, Oxford, 1993 6. T.S. Sahota et al., Drug Dev. and Industr. Pharm., 25, 307 (1999) 7. F.M. Gray, Polymer Electrolytes (Royal Society of Chemistry, Cambridge, 1997) 8. J.R. MacCallum and C.A. Vincent, Polymer Electrolytes Reviews (Elsevier, New York, 1987) Voll. I and II 9. P.G. Bruce and C.A. Vincent, J. Chem. Soc. Faraday Trans., 89, 3187 (1993) 10. L. M. Torell et al., Solid State Ionics53-56, 1037 (1992)

11. F. Muller-Plathe and W.F. van Gunsteren, J. Chem. Phys., 103, 4745-4756 (1995) 12. J. P. Donoso et al., J. Chem. Phys. 98, 10026 (1993) 13. A. Triolo, G. Visalli and R. Triolo, Solid State Ionics, 133, 99 (2000) 14. S. Passerini et al., J. Electrochemical Soc., 148, A1141 (2001) 15. G. B. Appetecchi and S. Passerini, J. Electrochemical Soc., 149, A891 (2002) 16. B. Frick and L. J. Fetters, Macromolecules, 27, 974 (1994) 17. A. Triolo et al., Physica B, 301, 163 (2001) 18. A. Triolo et al., Physica A, 304, 308 (2002) 19. C. Vachon, M. Vasco, M. Perrier and J. Prud’homme, Macromolecules, 26, 4023 (1993) 20. C. Vachon, C. Labreche, A. Vallee, S. Besner, M. Dumont and J. Prud’homme, Macromolecules, 28, 5585 (1995) 21. R. Bergman, L. Borjesson, G. Fytas, and L.M. Torell, J. NonCryst. Solids, 172-174, 830 (1994) 22. T. M. Connor, B. E. Read, and G. J. Williams, J. Appl. Chem., 14, 74 (1964) and C. H. Porter and R. H. Boyd, Macromolecules, 4, 589 (1971) 23. A. Dekmezian, D.E. Axelson, J. J. Dechter, B. Borah and L. Mandelkern, J. of Polym. Sci.: Polym. Phys. Ed., 23, 367 (1985) 24. B. Mos et al., Journal of Chemical Physics, 113, 4 (2000) 25. A. Bartolotta, G. Di Marco, M. Lanza, G. Carini, J Non-Cryst Solids, 172, 1195 (1994) 26. G. Di Marco, M. Lanza, M. Pieruccini, S.Campagna, Adv Mat 8, 576 (1996) 27. G. Di Marco, M. Lanza , A. Pennini, F. Simone, Solid State Ionics, 127, 23 (2000) 28. G. Di Marco, A. Bartolotta, G. Carini, J Appl Phys. 11, 5834 (1992) 29. F. Aliotta, G. Di Marco, R. C. Ponterio, F. Saija, C. Vasi, to appear on J. Colloids & Polymer Sci. (2002). 30. G. Mao, R. Fernandez Perea, W. S. Howells, D. L. Price, M. L. Saboungi, Nature, 405, 163(2000) 31. G. Mao, M. L. Saboungi, D. L. Price, M. Armand, F. Mezei, S. Pouget, Macromolecules, 35, 415 (2002.

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Articolo ricevuto in redazione nel mese di Dicembre 2002

THE DEVELOPMENT OF INSTRUMENTATION AT THE ILL C. J. Carlile Institut Laue Langevin, 38042 Grenoble, France

Abstract The ILL’s pre-eminent position, which it still enjoys today, was founded upon the implementation of high quality novel instrumentation ranging from the first full scale use of neutron guides to backscattering spectroscopy and small angle scattering. Equally well a constant element in the life of the ILL has been the development of new techniques for the future improvement of instruments. Supermirrors, focussing monochromators and position sensitive detectors are highlights of this process. The reactor itself was totally renewed in 1994 and will operate for at least the next 20 years. The internation convention has recently been extended to the end of 2013. In 1995 a modest programme of instrument renewal including the new reflectometer D17 and the liquids diffractometer D4 was started, which is now complete and bearing fruit. In 1999 however, the opportunity arose driven by the then Director Dirk Dubbers to implement a more ambitious programme of instrument renewal which would bring the performance of the Institut’s instruments back to the cutting edge of neutron technology, in many cases using techniques developed at the ILL, such as the use of polarised 3He. In addition a marked deterioration in the performance of the elderly neutron guides – many installed at the birth of the Institut – has been observed. This drop in delivery efficiency of the neutrons to the guide halls is being reversed by a systematic renewal of these guides. Drops in transmission as great as 40% have been observed. To replace some of these guides with supermirrors would bring substantial gains in intensity at the instruments. Thus in January 2000 the Millennium Programme was formally launched with funding from within the Institute’s own budget for five instrument projects including a new image plate diffractometer VIVALDI (see the front cover). This programme was received with enthusiasm by the user community and by our funding authorities and, encouraged by this support, other projects have been included for 2001 and 2002 and individual capital bids have been made successfully to national and international funding bodies, driven by groups of users. Furthermore the Institute’s infrastructure, such as the ageing neutron guides, was also the subject of re-examination. The aim behind the Millennium Programme has been to

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set in place a continuous programme of instrument renewal. Analysis shows that the major cost of an instrument is its operation and not its capital cost and therefore maintaining every instrument at the highest technical standard is extremely cost effective. In parallel a broader strategic study of opportunities available to the Institut has been published in the ILL’s Road Map which gives directions for the future evolution of the Millennium Programme. 1. Introduction The ILL has always had a strong tradition of both instrument development and of neutron technique development. Indeed the imaginative application of innovative technology in the 1970s, notably neutron guides, was the determining reason why the centre of gravity of neutron scattering shifted to Europe from the United States, where it has remained ever since. The Brookhaven reactor, built a few years earlier, was conservatively instrumented and remained a facility which served its own research programme rather than that of an outside user community, in direct contrast to the ILL, and it is fair to say that it has not had the overall broad scientific impact of the ILL. Amongst these innovations one can point to: small angle scattering; microelectronvolt spectroscopy; the production and use of ultra cold neutrons; tanzboden triple-axis spectrometers; the use of extended detector arrays and one and two dimensional position sensitive detectors; variable temperature cryostats and dilution refrigerators; the implementation of focussing monochromators and analysers; the realisation of neutron spin-echo; polarising devices including supermirrors and helium-3; and the ability to handle a wide range of samples from bacteria and viruses to transuranic compounds. One should not forget either the pioneering work in neutron physics – the half-life of the neutron, the search for a non-zero value of the electric dipole moment of the neutron, neutron interferometry, and gamma ray and fission spectroscopy – which has brought great distinction to the Institut, nor indeed the Theory Group which has, at one time or another, welcomed virtually all the top-class condensed matter theoreticians in the world. The Institut is centred around a high flux research reactor operating at 58MW. Its single-element highly com-

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pact core makes it the most intense slow neutron source in existence. The reactor, furnished with two cold sources and one hot source, supplies neutrons to ~40 instruments, 25 of which are fully scheduled for the user programme, and 8 CRG instruments partially scheduled for users, together with a number of special instruments and test beams. These instruments are available to scientists from the ILL’s nine partner countries for their re-

ed programme of instrument renewal was set in place that is now bearing fruit. During 2000 and 2001 we welcomed the integration into the user programme of: • the D17 reflectometer, able to be operated as a time of flight machine or a monochromatic beam instrument and with polarised and non-polarised beam options. A time of flight pattern from a ruled diffraction grating is shown in Figure 2.

Fig. 1. Papers published on neutron scattering in top level journals from 1998-2002.

search. The reactor normally operates for 225 days each year providing over 6000 instrument-days for science. The ILL welcomes ~ 1500 individual researchers each year, who carry out ~ 750 experiments and publish over 500 papers annually. In a survey of papers published in the top journals (Phys. Rev. Letters, Phys. Rev. & Nature) the ILL’s output in neutron scattering accounts for almost 40% of world output as shown in Figure 1. The Institut was set up as a purpose-built user facility – the first of its kind – and provides today a complete infrastructural backup (scientific local contacts, sample environment facilities, sample preparation laboratories, data manipulation and visualisation, a 160-bedroom guesthouse, a restaurant and a library…) in order that users might derive the most from their hard-won beamtime. On a site shared by the European Synchrotron Radiation Facility and the European Molecular Biology Laboratory, the three International Institutes constitute an unparalleled world centre for condensed matter studies. With the rebuild and upgrade to the reactor having been completed in 1994, the ILL put all its energies into relaunching the user programme. At the same time a limit-

• the rebuilt D4 liquids diffractometer with 5 times increase in luminosity and 5 times improvement in detector stability using the very stable microstrip detectors developed at ILL. The instrument layout and the improvement in detector stability is shown in Fig. 3. • the new IN4 chopper spectrometer with a 7 times increase in intensity and its low angle detector, a collaboration with INFM Italy. • the IN15 time-of-flight spin-echo spectrometer, the first such machine of its kind and a prototype for spinecho instruments on pulsed sources, which is a collaborative venture with FZ Jülich. • the mark-II version of the D20 diffractometer with its upgraded microstrip detector continuously covering 160° of scattering angle with an angular resolution of 0.1°. The new instrument is shown in Figure 4. In addition, for 2002, we recently have brought back into service the IN5 spectrometer following the total rebuild of its primary spectrometer. First neutrons on the instrument (November 2002) show a measured gain of precisely 10 in intensity at 5Å for the same nicely-defined triangular resolution. The new incident beam layout and the aluminium disc choppers are shown in Figure 5. The to-

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tally rebuilt IN8 triple-axis spectrometer, a collaboration with CSIC Spain, is now taking users and, with the implementation of a “virtual source” and its three-sided doubly focussing monochromator, the intensity on the sample is up by a factor of 3 to 5 depending on the configuration chosen, the resolution has been improved and the maximum energy transfer has been extended from 45 meV to greater than 70 meV. Whenever advantage can be taken of horozontal focussing, for example for magnetic studies, total gain factors of between 10 and 25 can be achieved over the old instrument. The new instrument is shown in Figure 6.

Fig. 2. The D17 reflectometer can operate in monochromatic beam or time of flight options. Here we show a reflectogram from a ruled grating showing the different orders from the through beam nd the diffracted beam.

Towards the end of the last decade however, it became clear that the rebuild of the reactor, a very positive event in itself, had delayed the maintenance of ILL’s instruments and infrastructure at the cutting edge of neutron technology, much of which, like supermirrors and polarised helium-3, had been developed at ILL but never fully implemented on its own instruments. Accordingly the ILL formally launched its Millennium Programme on 1st January 2000 after wide consultation with the User Community. The Millennium Programme is intended to be a continuous and accelerated programme of investment in instrumentation and infrastructure so as to improve the overall output of the instrument suite by between a factor of 10 to 20 on average. At the end of 1999 the French, German and British

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Associates of the ILL gave the go-ahead for the start of five instrument projects from within economies in the ILL’s own budget with the intention to add two further projects each year thereafter. All five projects are now well advanced: • The rebuild of the single crystal diffractometer D3 as a spherical polarimeter is moving ahead progressively. It is conceptually and technologically complex and will come on line gradually over a three year period of development and commissioning. Decpol, a spin sensitive detector for the new instrument, comprising a polarised He3 spin filter plus a He3 detector within its magnetic shield, is already operational on the instrument. The new generation of Cryopad, shown in Figure 7 together with similar devices for IN22 (CEA CRG) and TAS1 at JAERI, which determines the (_,_) rotation of the neutron beam polarisation as it interacts with the sample, has been delivered to ILL, and is awaiting the installation of the Larmor precession coils. The new version of Cryopad will be able to host a standard dilution fridge, a thintailed cryostat which E and H fields can be applied simultaneously in order to determine the balance of magnetic domains in the sample, and a pulsed-tube cryo-refrigerator including a sample orientation cradle. Over the coming two years a non-polarising copper monochromator in combination with a polarised He3 spin filter will be installed on the incident beam side of the instrument. • An order of magnitude increase in measured polarised neutron flux to 8.8x107 n cm-2s-1 on the sample at a neutron energy of 50meV has been obtained by the remodelling of the IN20 primary spectrometer. Just as significant is the fact that the energy transfer range has been almost doubled thanks to this increase in luminosity. A larger diameter beam tube using a source size of 170 mm together with apertures which constitute a virtual source as on IN8 was installed in January 2001 and a new large area (230 mm x 140 mm) doubly focussing Heusler monochromator, grown in-house, was installed in April 2001. In addition the fast background has been reduced by the addition of a sapphire filter in the incident beam. The analyser and the new instrument in its spin-echo option is shown in Figure 8. A rebuild of the analysers is now following, thus making IN20 the finest polarisation analysis triple axis in existence. Present indications are that what was achieved in a complete cycle before the rebuild will be able to be done in a single day on the completed new instrument. The opportunities are manifold. • 2MHz detector for SANS. A rebuild of the detector of the D22 small angle scattering instrument is underway following a 2 year R & D programme with the

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aim of lifting the measurable date rate to 2 MHz. This programme has resulted in the development of thin (7 mm internal diameter) 1-metre long linear position sensitive He3 detectors from the commercially available 25 mm diameter detectors. Purpose-built high speed electronics to handle the high count rates foreseen at the spatial resolution required have also been designed and tested. The aim of achieving a position resolution of 7 mm along the length of the detector by an appropriate balance of absorber and quench gases and anode voltage has been exceeded in recent tests â&#x20AC;&#x201C; 3 mm can be achieved. An array of

128 such detectors are to be installed which will deliver the appropriate pixel resolution (7 mm x 7 mm) for the D22 and, shortly thereafter we hope, the D11 small-angle scattering instruments at an overall count rate exceeding the original 2 MHz specifications. Commissioning tests indicate that a rate of 5 MHz may be achievable. Currently these instruments are limited to around 50 kHz and must use beam attenuators, a serious misuse of the potent cold neutron flux, in order to avoid data corruption, even with the detectors situated at large distances from the sample. A one-hundred-fold increase in data rate will now al-

Fig. 3. The D4 liquids and amorphous diffractometer has been rebuilt using microstrip detectors. The stability of the detector has been significantly improved and the detected solid angle increased by a factor of five.

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low complex & demanding experiments, previously only dreamed of, to be tackled. • The Strain Imager is a joint project with the University of Manchester. Beam line design is complete, integrating D1A, D1B, the Strain Imager and VIVALDI along the same upgraded neutron guide. The site for the instrument has already been prepared in order to provide the necessary stability to support the 1 tonne capacity, 50 _m precision hexapod sample orientation device (a Stewart platform similar to airline pilot training simulators) which will sit on a granite table floating on a marble tanzboden floor. A CAD draw-

LADI diffractometer allowed important improvements in efficiency to be made, for example neutron illumination and laser read-out from the same side of the image-plate. E F Schumacher’s catch phrase Small is Beautiful appears to apply here. Certainly speed of manufacture, relative cheapness and small sample size, are all qualities in favour of such instruments. Gary McIntyre, the Vivaldi project scientist, is pursuing his claim that single crystal diffraction will now rival powder diffraction in speed, but of course powder diffraction is not standing still ! In response to the launch of the Millennium Programme

Fig. 4. The powder diffractometer D20 has been furnished with a totally rebuilt microstrip detector covering 160 degrees of scattering angle continuously. Optical fibre communications mean that data rates are high and delays in run stop-start are reduced to 50 ms second. Time-dependent measurements are thus ideally suited to this instrument.

ing laid onto the construction site is shown in Figure 9. This purpose-built engineering instrument will be a welcome addition to the ILL’s instrument suite, adding further breadth to the scientific programme. • VIVALDI, the Very Intense, Vertical Axis, Laue Diffractometer with its 50 _m resolution image plate detector has been operational now for over a year, with the distinction of being the first completed instrument of the ILL’s Millennium Programme. Delivery of the complete instrument took place at the end of May 2001 and it was installed on its guide position in June 2001. High-quality data sets can be obtained in a very short time – only a few hours – but more importantly sample sizes are very small, which is particularly relevant for the study of new materials or for biological samples. A recent study of magnetic scattering from FeTaO6 is shown in Figure 10 together will an inset photograph of the instrument itself on its end of beam position. Previous experience on the

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there followed a number of other significant events: • the increase in the UK contribution to the ILL, rising progressively from 25% in 2000 to 30% in 2003, and to 33% equality with the other Associates from 2004 onwards. The ILL recently witnessed the signing, by the French Minister of Research and the German and British Ambassadors, of the formal extension of the ILL’s international convention until 31st December 2013. • a recognition by the ILL Associates that the infrastructure of the Institut needs to be systematically renewed, • the setting of the Millennium Programme into a more wide-ranging strategy – the ILL Road Map. • a willingness to accept that user-driven bids for funds to upgrade instruments be incorporated into the ILL’s culture. During 2001 and 2002, the second and third years of the Millennium Programme, five further instrument projects

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have been started, along with a number of infrastructural improvements: • Super D2b, the high resolution powder diffractometer is being totally rebuilt with a cold focussing monochromator and a continuous position-sensitive detector and associated collimators. A sum of 100 k has been given awarded to the University of Caen and a team of users, led by Dr Paul Attfield, of Cambridge University, has been successful in gaining a capital grant of almost 1 M for 50% funding of this instr ument. • The D19 fibre and large unit cell single crystal diffractometer pioneered structural biology work with

isotopes, shown in Figure 12, is currently inexplicable. Whilst knowing that elements heavier than A=56 can only have been generated in supernova explosions, the pathways to these elements is only dimly glimpsed. Particularly important is information on the so-called waiting-point nuclei at the extreme edge of the neutron dripline, which are relatively long-lived and beyond the time scales of other methods. The installation of gamma coincidence detectors on the Lohengrin beamline promises a hundred fold increase in sensitivity at one hundredth of the cost of other methods proposed, for isotopes in

Fig. 5. For spectroscopy in the 10 to 50 microelectronvolt resolution range, IN5 has been the instrument of choice for 25 years. A rebuild of the primary spectrometer – the guide and the chopper system – has brought an increase in data rate of a factor 10 precisely.

neutrons but suffered from a limited luminosity. This will now be rectified by the refurbishment of the secondary spectrometer and the addition of four large 2D area detectors which will increase the data rate by nearly 20 times. A prototype detector, a microstrip device, is shown in Figure 11. The complementarity between synchrotron radiation and neutrons will be enhanced by this initiative which has been the subject of a successful capital grant award of 1 M to a user group led by Professor Judith Howard from Durham. • The neutron dripline detector on Lohengrin. There are three big questions in science, one of which is “What is the origin of the Universe?” The experimentally observed cosmological distribution of the

the decay spectrum from fission ringed in the figure. • The 40 metre long collimation mechanism for the D11 small angle instrument is now 30 years old. The front section has just been replaced, together with its equally ancient neutron guide, thereby delivering better reliability and higher intensity. An identical spare neutron velocity selector has been bought which has allowed the beamline design to be simplified and unnecessary gaps in the guide to be closed. Overall so far in the project, taking into account the additional flexibility in collimation lengths, an improvement in luminosity of a factor two has been achieved. • The D7 polarisation analysis diffuse scattering instrument was a tour de force when it was built, but

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in spite of this only demonstration experiments, which pointed out the opportunities made possible with such measurements, were feasible. A total upgrade of the instrument, requiring a heavy investment in large area supermirror polariser technology, will transform the scientific applicability of the instrument. An upgrade of the incident beam polariser and monochromator optics has resulted in a gain in the primary flux of a factor three. A prototype large area analyser has also been manufactured and tested and shows a measured gain in quality factor per unit area of 3 with respect to the old analysers. Coupled

Fig. 6. The monochromator for IN8 is a three-faced doubly focussing monochromator built in Spain, and furnished with monochromators – copper, germanium and graphite - from the ILL’s Optics Group.

to an increase in solid angle of the secondary spectrometer by a factor of 4.6, the overall gain in data rate of the new instrument will exceed a factor of 40. • The neutron guide for D1A, D1B, the Strain Imager and Vivaldi is to be renewed. Monte Carlo simulations show that gains averaging a factor of four can be achieved by the application of supermirror technology coupled to a much improved surface quality and better construction techniques than were available three decades ago. Two other support laboratories are being built:

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A bacteriological deuteration laboratory, jointly with EMBL, which has attracted a grant of 1,3 M to Professor Watson Fuller, Keele University and colleagues. Dr Dean Myles (EMBL) & Dr Trevor Forsyth (ILL) have recently succeeded in obtaining an additional 1M funding from the EU for this project. This laboratory will form part of a larger initiative – the Partnership for Structural Biology – launched by ESRF, ILL & EMBL together with the IBS Grenoble in November 2002. • A facility for materials engineering, FaME, jointly with ESRF, headed by Professor Peter Webster, Sal-

Fig. 7. The Cryopad device, developed over many years at ILL, is the ultimate device for exploiting the polarisation of the neutron spin as it interacts with the sample under study. A new version of cryopad, totally updated, is to be installed on the D3 polarised neutron diffractometer as part of the Millennium Programme.

ford which will key in well with the new Strain Imager and the engineering instruments at the ESRF, which are to be upgraded. This laboratory was officially inaugurated also in November 2002. In coming years the Millennium Programme will continue as a vehicle to upgrade instruments and to build new ones – the IN16 backscattering instrument, the Brillouin scattering instrument BRISP, the LADI diffractometer on

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a significantly enhanced cold beam, the full-sized neutron dripline detector, a horizontal surface reflectometer, a rebuild of the original IN11 spin-echo spectrometer, the PASTIS thermal TOF polarisation analysis instrument and an upgrade to the IN1 molecular spectrometer, and so on. We encourage collaborative ventures with our user community and our funding bodies in order to push forward into existence the many ideas which are now flowing. As part of the infrastructure upgrades a high-field cryomagnet with fields up to 15 T has been delivered and commissioned. Its first proving tests on the IN14 triple

end of 1999. The hot source has now been rebuilt – a not inconsiderable task since the original design had been engineered more than 30 years ago – and it should be reinstalled by spring 2003. As if to emphasise the contrary nature of life, a leak in the IN1/D4 beam tube was detected in summer 2002 and all three beam tubes viewing the hot source have now been removed as a precautionary measure. The rectangular cross-section beam tubes are being redesigned and we hope to have the first of these ready for installation in late summer 2003. Hardware improvements are only one side of the equation however. Nowadays in order to obtain the highest

Fig. 8. Triple axis spectroscopy with full polarisation analysis has up to now been limited by the available fluxes of polarised neutrons. This situation has been changed by the total renewal of the primary spectrometer of IN20 with an enlarged beam tube, a virtual source and a remarkable Heusler monochromator, grown and built in-house, which together yield an order of magnitude gain of flux on the sample.

axis spectrometer in early December 2002 have given valuable insight into the problems of operating such powerful devices. On a more mundane level the ILL’s park of 56 diffusion pumps is being totally renewed with modern technology turbo pumps. Such measures, which are not always obvious to the user, but result in a significant improvement in reliability. On a less positive note, the hot source instruments IN1, D4, D3, & D9, have not been able to take high energy neutrons since the failure of the hot source at the very

Fig. 9. A hexapod sample orientation table, used in flight simulators for pilot training, can manipulate heavy loads precisely and smoothly. On the Strain Imager, currently under construction at ILL, such a device will be used as an integral part of the new instrument.

quality scientific output, the user support infrastructure has also to keep pace with the improvements in instrumentation. This we are doing in consultation with our users through a regular series of User Forums which take advantage of the presence of 50 to 60 scientific visitors on site at any one time during operational periods, bringing them together to offer us guidance and advice.

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Christian Vettier coined the phrase “Offering more than just neutrons” and by this we mean, for example, the putting in place of a proper system of out of hours technical support, as well as specialised laboratories – such as FaME and the PSB discussed above – to provide a focus for specific groups of users. Responsiveness to the users’ needs is very important and the introduction of a

2. Outlook A sustained effort has been devoted over the last eighteen months into establishing a solid foundation for the regeneration of the Institute’s instruments and infrastructure through the launching of the ILL’s Millennium Programme. Perhaps it is more than symbolic that ILL is an integral part of the word millennium. Such an

Fig. 11. The D19 single crystal diffractometer has made some groundbreaking measurements, notably the precise location of water along the DNA double helix. Such experiments have provided a glimpse of what the power of an instrument, twenty times enhanced in detected solid angle, will be able to achieve. Here a prototype microstrip detector, developed in-house, shows great promise as one possible option for the instrument upgrade.

Fig. 10. The image plate single crystal diffractometer Vivaldi, is now available for users. Data on magnetic scattering from FeTaO6 Chung, Balakrishnan, Visser, Paul and Macintyre.

totally web-based proposal handling system integrated into the ILL’s recently launched User Club has proved very popular. Not only does it allow users to finalise their proposals up to a few minutes before the deadline but it also has allowed the time gap between proposal deadline and scientific review to be reduced.

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ambitious programme requires a concurrence of three essential ingredients – motivated and well-qualified manpower, adequate sources of finance, and inspired ideas. It also requires good luck and a willingness to take risks. As the first year of the Millennium Programme draws to a close, there are strong signs that all these elements are in place. Building upon the newly rebuilt reactor, the momentum generated by instrument projects already in place, the increasingly youthful staff and the guidance of our users, our funding bodies have all the evidence which they can possibly need to respond positively and unequivocally to our appeal for the investment necessary to fulfil the vision which is illustrated in the ILL’s long-term strategy document – the Road Map. Therefore, as we look ahead to the next 20 years and beyond, we envisage a bright future for researchers using the ILL in a renewed partnership with the Institut to fully realise the value of the 1.5 B capital invested and to optimise the scientific output to all partners. Whilst the present output is unquestionably second to none, quantity, quality and reliability can be even further enhanced in a cost-effective manner by the relatively modest in-

Vol. 8 n. 1 Febbraio 2003


RASSEGNA SCIENTIFICA

vestment in instrumentation which the ILLâ&#x20AC;&#x2122;s Millenium Programme represents.

received from our users and representatives of our partner countries.

3. Acknowledgements We wish to heartily thank all those ILL staff who have contributed so energetically to the launch of the Millennium Programme, and to the encouragement we have

Fig. 12. There has been a strong revival in exploring the extreme fringes of stability of the distribution of the nuclides in recent years. On Lohengrin, a region which is particularly important in understanding the dynamics of reaching the present-day distribution, can be accessed at ILL, which is the region at the edge of the doubly peaked fission fragment distribution. This area can be accessed with a sensitivity one hundred times increased, by using gamma coincidence counting.

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PROGETTO E.S.S.

THE ESS MAINTAINS MOMENTUM AND ENTERS THE DECISION PHASE After the presentation in Bonn, the European Spallation

Malacarne and Ms. Elena Righi from the unit for Re-

Source project has felt the full impact of being in the de-

search Infrastructures in EU’s DG Research. ESFRI began

cision phase. Several recent events have caused both

the discussion about neutrons last summer and now a

positive and negative publicity about the project. But in

working group is analysing potential scenarios for neu-

general the project show remarkable progress.

trons in Europe: one being ESS, another upgrading ISIS

The discussion on scenarios for neutrons in the future

and ILL. Its report should be ready by the end of 2002.

European Research Area has started. The decision on im-

That report and the ensuing discussion within the ESFRI

proving, maintaining or closing the existing large facili-

Forum itself will be the basis for decisions on the future

ties or create new ones is a complex process. To promote

ESS strategy by the ESS Council in early 2003.

a coherent policy the European Commission has estab-

A clear indication of the ESS advancement is that the

lished the ”European Strategy Forum on Research Infra-

project maintains its European outlook and its scientific

structures” ESFRI. It provides a multidisciplinary plat-

relevance. The ESS Council, in the meeting held in

form to monitor major installations including scientific

Frankfurt on October 26,2002, has reconfirmed its deci-

facilities as well as virtual libraries in the humanities or

sion to complete the baseline for ESS by the end of 2003.

networks of ecological reserves. The Forum comprises

The Memorandum of Understanding entered into force

representatives of each of the 15 Member States appoint-

last month, when 2/3 of the estimated partners had

ed by its own Research Ministers. ESFRI’s chairman is

signed the agreement to continue their efforts to design

Dr. Hans Chang (NL), who is director of the Nether-

and construct a European next generation Spallation

lands’ Physics Research Council (part of the general Re-

Source. The full list of partners is: Atominstitut Vienna,

search Council NWO); secretaries are Dr. Marco

Austria; CCLRC, UK; Ciemat, Spain; CNR, Italy; FZJ, Germany; HMI, Germany; INFM, Italy; IRI Delft, The Netherlands; JINR, Russia; PSI, Switzerland; Risø National Laboratory, Denmark; Univ. Frankfurt, Germany; Univ. Latvia, Lettland, Univ. Uppsala, Sweden. All partners except CEA in France have now signed the MoU. The CEA left for budgetary reasons and lack of personnel (the ESS french team was required for the funded SPIRAL-II project at GANIL), but still wishes to remain as an observer in the ESS Council. The ESS Council very much regrets that decision, but feels strongly encouraged by the support the french scientists and instrument team members keep giving to the ESS. It was also decided that the CEA contributions on accelerators, conventional facilities and costing will be take over by the other ESS partners. To further strengthen the ESS it is being set up as a private company on the basis of German law. It will be called ESS GmbH and will enable stronger central control, and the possibility to act legally for ESS. A GmbH is a limited liability company (“Gesellschaft mit

Kurt Clausen

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Vol. 8 n. 1 Febbraio 2003


PROGETTO E.S.S.

beschränkter Haftung”), which is a standard legal form

(UK), Jülich (D), Leipzig-Halle (D), Lund (S) and York-

for a company, in our case a non-profit company. ESS

shire (UK) – have not only prepared their candidatures

GmbH is a vehicle for ESS, and for ESS only. It will

presented at the Bonn Conference, but also they have

therefore be under full control of the ESS Council and

started collaborations to join efforts to get ESS funded.

be operated by the Project-Directorate. Its purpose is to

A first meeting was held in Düsseldorf on September 20,

facilitate the carrying out of the work program estab-

2002.

lished by the Council.

Between the actions initiated to promote the ESS a

The ESS Council has responded to the issues raised by

newsletter will inform scientists, media, governments,

the Wissenschaftsrat in Germany, and formally submit-

industry and the public about what happens in and out-

ted the Bonn volumes I-IV for further consideration by

side ESS. Find more information in our newsletter:

the WR. A letter has been written to the WR by the Hälg

http://www.ess-europe.de

Prize Committee in which these eminent scientists, among them two Noble prize winners Karl Alexander Müller (high Tc superconductivity,

F. Carsughi

physics) and Richard R. Ernst (Fourier-transform NMR, Chemistry) strongly reject the WR’s view that neutrons have no future. The ESS Council has appointed Kurt Clausen as the new ESS Project Director. He succeeds Jean-Louis Laclare, to whom ESS owes gratitude for the way he has led the project. A preliminary assessment show that the ESS could be build at any of the five sites that expressed interest to host it.. The sites – Chilton

Vol. 8 n. 1 Febbraio 2003

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VARIE

NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE

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Vol. 8 n. 1 Febbraio 2003


CALENDARIO

22-25 gennaio 2003

18-23 maggio 2003

2th International Workshop on Dynamics in Confinement (CONFIT)

13th IEEE-NPSS Real Time Conference

19-28 maggio 2003 10-11 febbraio 2003

10-11 febbraio 2003

8-11 giugno 2003

Membrane Structure and Function

LECCE, ITALY

10th European Workshop on Metalorganic Vapour Phase Epitaxy

GRENOBLE, FRANCE 21-26 giugno 2003 CASTELVECCHIO PASCOLI, ITALY

13th ESRF Users Meeting http://www.esrf.fr

12-14 febbraio 2003

TRIESTE, ITALY

School on "Magnetic Properties of Condensed Matter Investigated by Neutron Scattering and Synchrotron Radiation"

Inelastic X-ray Scattering in Disordered Systems and Soft Condensed Matter

10-14 febbraio 2003

MONTREAL, CANADA

Biological Surfaces and Interfaces EuroConference on Understanding and Improving Specific Interactions GENOVA, ITALY 1-11 luglio 2003

Silicon Workshop 2003

COMO, ITALY

International School of Physics “Enrico Fermi” 13-14 febbraio 2003

GRENOBLE, FRANCE 14-19 luglio 2003

X-ray detectors: the way to get more out of your beamline! ESRF

22 febbraio - 6 marzo 2003

New Frontiers in NanoBiotechnology: monitoring protein function with single-protein resolution

TEHRAN, IRAN

International Workshop on Physics and Technology of Thin Films (IWTF2003) Sharif University of Technology in Tehran, Iran

27 febbraio - 1 marzo 2003

FRASCATI, ITALY

Methods for Biological Applications - Advances in experimental and theoretical methods for biological applications of Synchrotron Radiation Workshop

23-25 luglio 2003

FIRENZE, ITALY

LDM2003: International Conference on "Theoretical Trends in Low-Dimensional Magnetism

27 luglio-1 agosto 2003

ROMA, ITALY

ICM 2003: International Conference on Magnetism

28 luglio-1 agosto 2003 15-22 marzo 2003

TRIESTE, ITALY

ERICE, ITALY

MODENA, ITALY

13th International Conference on Nonequilibrium Carrier Dynamics in Semiconductors ( HCIS13 )

Advances in Quantum Information Processing: from Theory to Experiment 3-8 agosto 2003

SAN DIEGO, CALIFORNIA

SPIE Symposium on Nanocrystal Optics 2003

Vol. 8 n. 1 Febbraio 2003

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CALENDARIO

4-7 agosto 2003

VENEZIA, ITALY

International Conference on Polarized Neutrons and Synchrotron X-rays for Magnetism (PNSXM 2003) A satellite of the International Conference of Magnetism, Rome 2003. R. Caciuffo, Dip. di Fisica ed Ingegneria dei Materiali e del Territorio, I.N.F.M., Univ. di Ancona, Via Brecce Bianche, 60131 Ancona, Italy. Tel: +39 071 2204423; Fax: +39 071 2204729 E-mail: rgc@unian.it http://venice.infm.it http://www.icm2003.mlib.cnr.it

8-9 settembre 2003

MANCHESTER, U.K.

2nd International Conference MECA-SENS http://isis.rl.ac.uk

14-18 settembre 2003

SORRENTO, NAPOLI, ITALY

EUCAS 2003: 6th European Conference on Applied Superconductivity

15-18 ottobre 2003

BADAJOZ, SPAIN

First International Meeting on Applied Physics (APHYS-2003) 26-30 agosto 2003 Highly Frustrated Magnetism 2003

28 nov - 2 dic 2005

SYDNEY, AUSTRALIA

2005 International Conference on Neutron Scattering 3-6 settembre 2003

MONTPELLIER, FRANCE

Third European Conference on Neutron Scattering N. Malartic, ECNS 2003 Conference Office, U. Montpellier II, Case 069, F-34095 Montpellier Cedex 5, France. E-mail: info@ecns2003.org http://www.ecns2003.org

NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE

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â&#x20AC;˘

Vol. 8 n. 1 Febbraio 2003


SCADENZE

Scadenze per richieste di tempo macchina presso alcuni laboratori di Neutroni

Scadenze per richieste di tempo macchina presso alcuni laboratori di Luce di Sincrotrone

ISIS

ALS

La scadenza per il prossimo call for proposals è il 16 aprile 2003 e il 16 ottobre 2003

Le prossime scadenze sono il 15 marzo 2003 (cristallografia macromolecolare) e il 1 giugno 2003 (fisica)

ILL BESSY

La scadenza per il prossimo call for proposals è il 26 febbraio 2003

Le prossime scadenze sono il 15 febbraio 2003 e il 4 agosto 2003

LLB-ORPHEE-SACLAY La scadenza per il prossimo call for proposals è il 1 ottobre 2003 per informazioni: Secrétariat Scientifique du Laboratoire Léon Brillouin, TMR programme, Attn. Mme C. Abraham, Laboratoire Léon Brillouin, CEA/SACLAY, F-91191 Gif-sur-Yvette, France. Tel: 33(0)169086038; Fax: 33(0)169088261 e-mail: abraham@bali.saclay.cea.fr http://www-llb.cea.fr

DARESBURY Le prossime scadenze sono il 30 aprile 2003 e il 31 ottobre 2003

ELETTRA Le prossime scadenze sono il 28 febbraio 2003 e il 31 agosto 2003

ESRF BENSC La scadenza è il 15 marzo 2003 e il 15 settembre 2003

RISØ E NFL La scadenza per il prossimo call for proposals è il 1 aprile 2003

Le prossime scadenze sono il 1 marzo 2003 e il 1 settembre 2003

GILDA (quota italiana) Le prossime scadenze sono il 1 maggio 2003 e il 1 novembre 2003

HASYLAB (nuovi progetti) Le prossime scadenze sono il 1 marzo 2003, il 1 settembre 2003 e il 1 dicembre 2003

LURE La prossima scadenza è il 30 ottobre 2003

MAX-LAB La scadenza è approssimativamente febbraio 2003

NSLS Le prossime scadenze sono il 31 gennaio 2003, il 31 maggio 2003 e il 30 settembre 2003

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FACILITIES DOVE LUCE DI SINCROTRONE

LUCE DI SINCROTRONE SYNCHROTRON SOURCES WWW SERVERS IN THE WORLD (http://www.esrf.fr/navigate/synchrotrons.html)

ALS Advanced Light Source MS46-161, 1 Cyclotron Rd Berkeley, CA 94720, USA tel:+1 510 486 4257 fax:+1 510 486 4873 http://www-als.lbl.gov/ Tipo: D Status: O AmPS Amsterdam Pulse Stretcher NIKEF-K, P.O. Box 41882, 1009 DB Amsterdam, NL tel: +31 20 5925000 fax: +31 20 5922165 Tipo: P Status: C APS Advanced Photon Source Bldg 360, Argonne Nat. Lab. 9700 S. Cass Avenue, Argonne, Il 60439, USA tel:+1 708 252 5089 fax: +1 708 252 3222 http://epics.aps.anl.gov/welcome.html Tipo: D Status: C ASTRID ISA, Univ. of Aarhus, Ny Munkegade, DK-8000 Aarhus, Denmark tel: +45 61 28899 fax: +45 61 20740 Tipo: PD Status: O BESSY Berliner Elektronen-speicherring Gessell.für Synchrotron-strahlung mbH Lentzealle 100, D-1000 Berlin 33, Germany tel: +49 30 820040 fax: +49 30 82004103 http://www.bessy.de Tipo: D Status: O BSRL Beijing Synchrotron Radiation Lab. Inst. of High Energy Physics, 19 Yucuan Rd.PO Box 918, Beijing 100039, PR China tel: +86 1 8213344 fax: +86 1 8213374 http://solar.rtd.utk.edu/~china/ins/IHEP/bsrf/bsrf.html Tipo: PD Status: O CAMD Center Advanced Microstructures & Devices Lousiana State Univ., 3990 W Lakeshore, Baton Rouge, LA 70803, USA tel:+1 504 3888887 fax: +1 504 3888887 http://www.camd/lsu.edu/ Tipo: D Status: O CHESS Cornell High Energy Synchr. Radiation Source Wilson Lab., Cornell University Ithaca, NY 14853, USA tel: +1 607 255 7163 fax: +1 607 255 9001 http://www.tn.cornell.edu/ Tipo: PD Status: O

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DAFNE INFN Laboratori Nazionali di Frascati, P.O. Box 13, I-00044 Frascati (Rome), Italy tel: +39 6 9403 1 fax: +39 6 9403304 http://www.lnf.infn.it/ Tipo:P Status: C DELTA Universität Dortmund,Emil Figge Str 74b, 44221 Dortmund, Germany tel: +49 231 7555383 fax: +49 231 7555398 http://prian.physik.uni-dortmund.de/ Tipo: P Status: C ELETTRA Sincrotrone Trieste, Padriciano 99, 34012 Trieste, Italy tel: +39 40 37581 fax: +39 40 226338 http://www.elettra.trieste.it Tipo: D Status: O ELSA Electron Stretcher and Accelerator Nußalle 12, D-5300 Bonn-1, Germany tel:+49 288 732796 fax: +49 288 737869 http://elsar1.physik.uni-bonn.de/elsahome.html Tipo: PD Status: O ESRF European Synchrotron Radiation Lab. BP 220, F-38043 Grenoble, France tel: +33 476 882000 fax: +33 476 882020 http://www.esrf.fr/ Tipo: D Status: O EUTERPE Cyclotron Lab.,Eindhoven Univ. of Technol, P.O.Box 513, 5600 MB Eindhoven, The Netherlands tel: +31 40 474048 fax: +31 40 438060 Tipo: PD Status: C HASYLAB Notkestrasse 85, D-2000, Hamburg 52, Germany tel: +49 40 89982304 fax: +49 40 89982787 http://www.desy.de/pub/hasylab/hasylab.html Tipo: D Status: O INDUS Center for Advanced Technology, Rajendra Nagar, Indore 452012, India tel: +91 731 64626 Tipo: D Status: C

Vol. 8 n. 1 Febbraio 2003


FACILITIES

SOR-RING Inst. Solid State Physics S.R. Lab, Univ. of Tokyo, 3-2-1 Midori-cho Tanashi-shi, Tokyo 188, Japan tel: +81 424614131 ext 346 fax: +81 424615401 Tipo: D Status: O

KEK Photon Factory Nat. Lab. for High Energy Physics, 1-1, Oho, Tsukuba-shi Ibaraki-ken, 305 Japan tel: +81 298 641171 fax: +81 298 642801 http://www.kek.jp/ Tipo: D Status: O

SRC Synchrotron Rad. Center Univ.of Wisconsin at Madison, 3731 Schneider DriveStoughton, WI 53589-3097 USA tel: +1 608 8737722 fax: +1 608 8737192 http://www.src.wisc.edu Tipo: D Status: O

Kurchatov Kurchatov Inst. of Atomic Energy, SR Center, Kurchatov Square, Moscow 123182, Russia tel: +7 95 1964546 Tipo: D Status:O/C

SRRC SR Research Center 1, R&D Road VI, Hsinchu Science, Industrial Parc, Hsinchu 30077 Taiwan, Republic of China tel: +886 35 780281 fax: +886 35 781881 http://www.srrc.gov.tw/ Tipo: D Status: O

LNLS Laboratorio Nacional Luz Sincrotron CP 6192, 13081 Campinas, SP Brazil tel: +55 192 542624 fax: +55 192 360202 Tipo: D Status: C LURE Bât 209-D, 91405 Orsay ,France tel: +33 1 64468014; fax: +33 1 64464148 E-mail: lemonze@lure.u-psud.fr http://www.lure.u-psud.fr Tipo: D Status: O

SSRL Stanford SR Laboratory MS 69, PO Box 4349 Stanford, CA 94309-0210, USA tel: +1 415 926 4000 fax: +1 415 926 4100 http://www-ssrl.slac.stanford.edu/welcome.html Tipo: D Status: O

MAX-Lab Box 118, University of Lund, S-22100 Lund, Sweden tel: +46 46 109697 fax: +46 46 104710 http://www.maxlab.lu.se/ Tipo: D Status: O NSLS National Synchrotron Light Source Bldg. 725, Brookhaven Nat. Lab., Upton, NY 11973, USA tel: +1 516 282 2297 fax: +1 516 282 4745 http://www.nsls.bnl.gov/ Tipo: D Status: O NSRL National Synchrotron Radiation Lab. USTC, Hefei, Anhui 230029, PR China tel:+86 551 3601989 fax:+86 551 5561078 Tipo: D Status: O Pohang Pohang Inst. for Science & Technol., P.O. Box 125 Pohang, Korea 790600 tel: +82 562 792696 f +82 562 794499 Tipo: D Status: C

SRS Daresbury SR Source SERC, Daresbury Lab, Warrington WA4 4AD, U.K. tel: +44 925 603000 fax: +44 925 603174 E-mail: srs-ulo@dl.ac.uk http://www.dl.ac.uk/home.html Tipo: D Status: O SURF B119, NIST, Gaithersburg, MD 20859, USA tel: +1 301 9753726 fax: +1 301 8697628 http://physics.nist.gov/MajResFac/surf/surf.html Tipo: D Status: O TERAS ElectroTechnical Lab. 1-1-4 Umezono, Tsukuba Ibaraki 305, Japan tel: 81 298 54 5541 fax: 81 298 55 6608 Tipo: D Status: O UVSOR Inst. for Molecular ScienceMyodaiji, Okazaki 444, Japan tel: +81 564 526101 fax: +81 564 547079 Tipo: D Status: O

Siberian SR Center Lavrentyev Ave 11, 630090 Novosibirsk, Russia tel: +7 383 2 356031 fax: +7 383 2 352163 Tipo: D Status: O SPring-8 2-28-8 Hon-komagome, Bunkyo-ku ,Tokyo 113, Japan tel: +81 03 9411140 fax: +81 03 9413169 Tipo: D Status: C

D = macchina dedicata; PD = parzialmente dedicata; P = in parassitaggio. O= macchina funzionante; C=macchina in costruzione. D = dedicated machine; PD = partially dedicated; P = parassitic. O= operating machine; C= machine under construction.

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FACILITIES

NEUTRONI NEUTRON SCATTERING WWW SERVERS IN THE WORLD (http://www.isis.rl.ac.uk) Atominstitut Vienna (A) Facility: TRIGA MARK II Type: Reactor. Thermal power 250 kW. Flux: 1.0 x 1013 n/cm2/s (Thermal); 1.7 x 1013 n/cm2/s (Fast) Type of instruments available to external users: SANS, Interferometer, Depolarisation, Transmission Expts, neutron radiography. Address for information: Atominstitut Oesterreichischen Universitaeten Stadionallee 2 A-1020 Wien Prof. H. Rauch Tel: +43 1 58801 14168; Fax: +43 1 58801 141199 E-mail: boeck@ati.ac.at http://www.ati.ac.at

BNL (USA) Brookhaven National Laboratory, Biology Department, Upton, NY 11973, USA Dieter Schneider; General Information: Rae Greenberg; Tel: +1 516 282 5564 Fax: +1 516 282 5888 http://neutron.chm.bnl.gov/HFBR/

Budapest Neutron Centre BRR (H) Type: Reactor. Flux: 2.0 x 1014 n/cm2/s Dates for proposal submission: June 15/November 15 Date for selection process: July/December Related scheduling periods: August-December/JanuaryJune. Address for application forms: Dr. Borbely Sándor, KFKI Building 10, 1525 Budapest, Pf 49, Hungary E-mail: Borbely@power.szfki.kfki.hu http://www.iki.kfki.hu/nuclear

FRJ-2 Forschungszentrum Jülich (D) Type: Dido reactor. Flux: 2 x 1014 n/cm2/s Dates for proposal submission: no formal selection process. Informal proposals to: Prof. D. Richter, Forschungszentrums Jülich GmbH, Institut für Festkörperforschung, Postfach 19 13, 52425 Jülich, Germany Tel: +49 2461161 2499; Fax: +49 2461161 2610 E-mail: d.richter@kfa-juelich.de http://www.kfa-juelich.de

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FRG-1 Geesthacht (D) Type: Swimming Pool Cold Neutron Source. Flux: 8.7 x 1013 n/cm2/s Dates for proposal submission: any time Dates for selection process: within 4 weeks of submission Address for application forms and informations: Reinhard Kampmann, Institute for Materials Science, Div. Wfn-Neutronscattering, GKSS, Research Centre, 21502 Geesthacht, Germany Tel: +49 (0)4152 87 1316/2503; Fax: +49 (0)4152 87 1338 E-mail: reinhard.kampmann@gkss.de http://www.gkss.de

HMI Berlin BER-II (D) Facility: BER II, BENSC Type: Swimming Pool Reactor. Flux: 2 x 1014 n/cm2/s NDates for selection process: May/November Related scheduling periods: July-December/JanuaryJune Address for application forms: Dr. Rainer Michaelsen, BENSC, Scientific Secretary, Hahn-Meitner-Insitut, Glienicker Str 100, 14109 Berlin, Germany Tel: +49 30 8062 2304/3043; Fax: +49 30 8062 2523/2181 E-mail: michaelsen@hmi.de http://www.hmi.de/

IBR2 Dubna (RU) Type: Pulsed Reactor. Flux: 3 x 1016 (thermal n in core) Dates for proposal submission: 16 October/16 May Dates for selection process: 30 January/15 September Related scheduling periods: February-June/OctoberFebruary Address for application forms: Dr. Vadim Sikolenko, Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia. Tel: +7 09621 65096; Fax: +7 09621 65882 E-mail: sikolen@nf.jinr.dubna.su http://nfdfn.jinr.dubna.su/

ILL Grenoble (F) Type: 58MW High Flux Reactor. Flux: 1.5 x 1015 n/cm2/s Dates for proposal submission: 15 February/31 August Dates for selection process: April/October Related scheduling periods: July-Decem./January-June

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FACILITIES

Address for application forms: Dr. G. Cicognani, Scientific Coordination Office, ILL, BP 156, 38042 Grenoble Cedex 9, France Tel: +33 4 7620 7179; Fax: +33 4 76483906 E-mail: cico@ill.fr and sco@ill.fr http://www.ill.fr

IPNS (USA) Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4814, USA P.Thiyagarajan,Bldg.200,RM. D125; tel :+1 708 9723593 E-mail: THIYAGA@ANLPNS Ernest Epperson, Bldg. 212; tel: +1 708 972 5701 fax: +1 708 972 4163 or + 1 708 972 4470 (Chemistry Div.) http://pnsjph.pns.anl.gov/ipns.html

IRI Delft (NL) Type: 2MW light water swimming pool. Flux: 1.5 x 1013 n/cm2/s Dates for proposal submission: no formal selection process Address for application forms: Dr. A.A. van Well, Interfacultair Reactor Institut, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands Tel: +31 15 2784738; Fax: +31 15 2786422 E-mail: vanWell@iri.tudelft.nl http://www.iri.tudelft.nl

ISIS Didcot (UK) Type: Pulsed Spallation Source. Flux: 2.5 x 1016 n fast/s ISIS operates at 200 µA in 0.4 µs pulsed at 50 Hz Address for application forms: ISIS Users Liaison Office, Building R3, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX Tel: +44 (0) 1235 445592; Fax: +44 (0) 1235 445103 E-mail: uls@isis.rl.ac.uk http://www.isis.rl.ac.uk

JAERI (J) Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-11, Japan. Jun-ichi Suzuki (JAERI); Yuji Ito (ISSP, Univ. of Tokyo); fax: +81 292 82 59227 telex: JAERIJ24596 http:// neutron-www.kekjpl

JEEP-II Kjeller (N) Type: D2O moderated 3.5% enriched UO2 fuel. Flux: 2 x 1013 n/cm2/s Dates for proposal submission: no special dates Dates for selection process: no special dates Address for application forms: Institutt for Energiteknikk K.H. Bendiksen, Managing Director, Box 40, 2007 Kjeller, Norway Tel: +47 63 806000, 806275; Fax: +47 63 816356 E-mail: kjell.bendiksen@ife.no http://www.ife.no

LLB Orphée Saclay (F) Type: Reactor. Flux: 3.0 x 1014 n/cm2/s Dates for proposal submission: September Dates for selection process: November Related scheduling periods: January-December Address for application forms: Mrs Claude Rousse, Laboratoire Léon Brillouin, CEASaclay, 91191Gif-sur-Yvette Cedex, France Tel: +33 1 6908 5241/5417; Fax: +33 1 6908 8261 E-mail: rousse@bali.saclay.cea.fr http://www-drn.cea.fr

NFL Studsvik (S) Type: 50 MW reactor. Flux: > 1014 n/cm2/s Dates for proposal submission: 1 December, 1 April, 1 August (for LSF programme only) Dates for selection process: Decisions before 1 January, 1 May, 1 September (LSF only) Related scheduling periods: January-April/MayAugust/September-December. Address for application forms: Dr. R. McGreevy, NFL Studsvik, S-611 82 Nyköping, Sweden Tel: +46 155 221000; Fax: +46 155 263070/263001 E-mail: kklingfeldt@studsvik.se http://www.studsvik.uu.se

NIST National Institute of Standards and TechnologyGaithersburg, Maryland 20899 USA C.J. Glinka; tel: + 301 975 6242 fax: +1 301 921 9847 E-mail: Bitnet: GLINKA@NBSENTH Internet: GLIMKA@ENH.NIST.GOV http://rrdjazz.nist.gov

NPI Rez (CZ) Type: 10 MW research reactor. Address for informations: Zdenek Kriz, Scientif Secretary, Nuclear Research Institute Rez plc, 250 68 Rez, Czech Republic

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FACILITIES

Tel: +420 2 20941177 / 66173428; Fax: +420 2 20941155 E-mail: krz@ujv.cz / brv@nri.cz http://www.nri.cz

ORNL (USA) Oak Ridge National Laboratory Neutron Scattering Facilities, P.O. Box 2008, Oak Ridge TN 37831-6393 USA George D. Wignall, Small Angle Scattering Group Leader Tel: +1 423 574 5237; Fax: +1 423 574 6268 E-mail: wignallgd@ornl.gov http://neutrons.ornl.gov

TU Munich FRM, FRM-2 (D) Type: Compact 20 MW reactor. Flux: 8 x 1014 n/cm2/s Address for informations: Prof. Winfried Petry, FRM-II Lichtenbergstrasse 1, 85747 Garching Tel: 089 289 14701; Fax: 089 289 14666 E-mail: wpetry@frm2.tum.de http://www.frm2.tu-muenchen.de

PSI-SINQ Villigen (CH) Type: Steady spallation source. Flux: 2.0 x 1014 n/cm2/s Related scheduling periods: January-June/JulyDecember. Address for application forms: Prof. Albert Furrer, Secretariat, Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institute, CH5232 Villigen PSI, Switzerland Tel: +41 56 3102088; Fax: +41 56 3102939 E-mail: albert.furrer@psi.ch http://lns.web.psi.ch

NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE

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Vol. 8 n. 1 Febbraio 2003


NOTIZIARIO Neutroni e Luce di Sincrotrone Vol. 8 n. 1 2003

Rivista del Consiglio Nazionale delle Ricerche

EDITORIALE C. Andreani

RASSEGNA SCIENTIFICA Interaction of Carbon Nanotubes with Adsorbates Studied by High Resolution Photoemission Spectroscopy R. Larciprete et al.

Polymer Electrolytes Dynamics as Probed by QENS F. Aliotta and A. Triolo

The Development of Instrumentation at the ILL C.J. Carlile

PROGETTO E.S.S. The ESS maintains Momentum and enters the Decision Phase F. Carsughi

VARIE CALENDARIO SCADENZE FACILITIES

ISSN 1592-7822

NOTIZIARIO Neutroni e Luce di Sincrotrone - Issue 8 n.1, 2003  

Notiziario Neutroni e Luce di Sincrotrone - published by CNR (Publishing and Promotion of Scientific Information) in collaboration with the...

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