12 PSI-XFEL
PSI Scientific Report 2008
Novel science at the PSI-XFEL
Bruce Patterson, Rafael Abela, Free Electron Laser Project (PSI-XFEL), PSI Kurt Ballmer-Hofer, Molecular Cell Biology, PSI, Laura Heyderman, Laboratory for Micro- and Nanotechnology, PSI; Chris Milne, Laboratory for Synchrotron Radiation, PSI and EPFL, Lausanne; Urs Staub, Pierre Thibault, Laboratory for Synchrotron Radiation, PSI
The PSI X-Ray Free Electron Laser (XFEL) facility will offer possibilities for novel science in condensed matter physics, chemistry and biology. The advantage of the XFEL over visible lasers and X-ray synchrotrons is the combination of short wavelength (0.1 – 10 nm), short pulse duration (<20 fs), high peak brightness, and high coherence. These properties will allow observations of time-dependent behaviour at the atomic level.
Scientific strengths of the PSI-XFEL
down to atomic resolution. Although a focused XFEL pulse will locally destroy the sample, the short pulse duration will ensure
The photon energies of the PSI X-ray Free Electron Laser (XFEL)
that the scattered photons reaching the detector arise from
[1] will allow a wide range of investigations of matter at the
undamaged material. Variable-polarization undulators at the
molecular and atomic level (see Figure 1). Furthermore, the
PSI-XFEL will allow observation of magnetization dynamics,
–14
s) and high
using the magnetic contrast of the L absorption features of,
peak flux (1011 photons/pulse) will permit the study of ultra-
for example, Fe, Co and Ni. Interesting magnetic processes
fast dynamics, either as equilibrium fluctuations or in “pump-
may be efficiently initiated at the PSI-XFEL with picosecond,
probe” experiments. XFEL-radiation has 100% transverse
half-cycle pulses of intense terahertz (THz) radiation, produced
coherence, allowing “lensless imaging” of nanostructures,
by a dedicated source, synchronized with the XFEL. The same
extremely short X-ray pulses (<20 fs = 2 10
THz source may also initiate surface catalytic reactions. It is also planned that the PSI-XFEL will deliver highly uniform, grating optics
crystal optics
“transform-limited” X-ray pulses, suitable for novel “quantum
Aramis
optics” techniques, such as heterodyne spectroscopy. Finally,
Porthos
the maximum photon energy of the PSI-XFEL may be suffi-
crystal diffraction
Arthos (seeded) d'Artagnan
ciently high to reach the ultra-narrow (10–8 eV) “Mössbauer
bio nanocrystals cell imaging
resonance” of the 57Fe nucleus, yielding the ultimate in highcoherence X-rays. In what follows, we briefly present three
stable Mössbauer isotopes 73
57
Ge Fe
magnetism, correlated e-
high-resolution spectroscopy Mg
Al
Si
P
Mn Fe
C
N
Bi
U
I La Ce Gd Ta W Pt Bi
O
water window
100
Cu
solution chemistry
Na M g Al Si P S
1000
Ca
Fe GaGeAs
proposed XFEL experiments of particular interest to PSI research divisions.
M edges 3
L edges 3
K edges
Nanoscale magnetic processes
104
Photon Energy [eV]
Very stable “magnetic vortices” in planar magnetic nanostructures may in the future be used for high-density information
Figure 1: The range of photon energy spanned by the beamlines
storage. Field-induced switching of the core of such a vortex
of the PSI-XFEL. Also indicated are preferred ranges for studying,
is predicted to occur on the nm and ps length and time scales
for example, organic materials in aqueous solution (“water
[2] (see Figure 2). With the high transverse coherence and the
window”), magnetism and correlated electron materials, and biological material in cellular and crystalline forms. The “M, L
circular polarization of the PSI-XFEL beam, and at photon
and K edges” refer to resonant energies of particular atomic
energies close to the magnetically-sensitive L2 and L3 edges
elements.
of, for example, cobalt (at 793 and 778 eV, respectively), it