Investigation of soft matter materials with the new system RISE combined with EDXS
R. Schmidt1,2, M. Nachtnebel2, H. Fitzek2, C. Mayrhofer2, H. Schröttner 1,2, A. Zankel1,2
1. Institute of Electron Microscopy and Nanoanalysis, NAWI Graz, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria 2. Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
Introduction At the Institute of Electron Microscopy and Nanoanalysis of Graz University of Technology (FELMI) together with the Graz Centre for Electron Microscopy (ZFE) the new system RISE (Raman Imaging and Scanning Electron microscopy) offers the possibility of high resolution imaging by the scanning electron microscope Zeiss Sigma 300 VP (Oberkochen, Germany) and chemical analysis with the attached Raman microscope from WITec (Ulm, Germany) [1,2,3]. Additionally the arrangement is equipped with a modern silicon drift detector from Oxford (UK) for energy dispersive x-ray spectroscopy (EDXS). This setup enables to distinguish different complex materials concerning layers, filler particles and additives and provides sample characterization in the same region of interest (ROI). This is realised in an uncomplicated manner by a stage movement (semi-automatically) between the SEM and the Raman measurement position in the specimen chamber. Different samples were investigated to present the possibilities of the new system [4].
RISE - Raman Imaging and Scanning Electron microscopy While SEM imaging and EDXS measurement are performed in one position of the specimen stage the Raman investigation is achieved by consecutive measurements enabled by the specimen stage movement (semi-automatically) between the SEM and the Raman measurement position in the specimen chamber, which is shown in Fig. 1. Thus chemical mapping (Raman) can be combined with high resolution SEM images and EDXS investigations.
Results a
Rutil
a
Figure 1. Movement of the specimen stage between SEM and Raman microscope inside the chamber, positions of different detectors and objective lens of the Raman microscope [4].
Figure 2. a) Correlative Raman-SEM image of different polymeric layers of a packing film; b) Raman spectra and component identification [4]. a
The analysis of a commercially available packing film gives a great impression how to display the different polymer layers by the Raman microscope (Fig 2). Results show in addition to a layered structure additives in one layer, which can be identified by Raman spectroscopy as rutil mixed into the PE matrix and were additionally analysed by automated EDXS particle analysis performed with the program AZtec from Oxford. Particles were classified in agglomerations, which indicates the occurrence of clusters of two or more particles and particles with additional subclasses “with Ti” and “without Ti”. The absence of the EDXS signal at the “without Ti”-group could be due the small size, where the electron penetration depth leads the X-ray generation in the particle surrounding, or a covering of particles by the PE matrix. The distribution of these particles is demonstrated in Fig 3a [4]. C
Conclusion First results of correlated electron microscopy, Raman microscopy and energy dispersive X-ray spectroscopy are more than distinct. However, to bring out the best of these measurements optimization concerning method and preparation has to be found to avoid beam damage or fluorescence, which is in progress.
Acknowledgment This work was enabled by the projects „HRSM-Project ELMINet Graz – Korrelative Elektronenmikroskopie in den Biowissenschaften“ (a cooperation within „BioTech Med-Graz“, a research alliance of the University of Graz, the Medical University of Graz and Graz University of Technology) and “Innovative Materialcharakterisierung“, SP2016-002006, which is part of „ACR Strategisches Projektprogramm 2016“ of the Austrian Cooperative Research (ACR).
Figure 3. a) TiO₂ particle layer; b) representative spectrum of one feature (number 1309) in this TiO₂-layer [4].
References/ Literature [1] C. Cardell, I. Guerra, An overview of emerging hyphenated SEM-EDX and Raman spectroscopy systems: Applications in life, environmental and materials sciences, Trends in Analytical Chemistry Volume 77, March 2016, 156-166 [2] A. A. Mironov, G. V. Beznoussenko, Correlative microscopy: a potent tool for the study of rare or unique cellular and tissue events, Journal of Microscopy, 235, 2009, 308-321 [3] Zeiss, Correlative Microscopy in Material Science, Microscopy and Analysis, Essential Knowledge Briefings, First Edition 2017 [4] R. Schmidt, H. Fitzek, M. Nachtnebel, C. Mayrhofer, H. Schroettner, A. Zankel, The combination of electron microscopy, Raman microscopy and energy dispersive X-ray spectroscopy for the investigation of polymeric materials, Macromolecular Symposia, Vol. 384, 1, 2019
Contact Email: ruth.schmidt@felmi-zfe.at Web.: www.felmi-zfe.at