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| Home > Publications database > Studies of atomic scale diffusion by quasielastic Mößbauer spectroscopy and x-ray photon correlation spectroscopy |
| Poster | DESY-2014-01372 |
; ;
2013
Abstract: Quasielastic Mößbauer Spectroscopy (QMS) has proven successful in investigating diffusive dynamics at the atomic level in solid state physics [1]. Due to the high energy resolution that is demanded by such experiments, it is however restricted to systems at rather high temperatures (close to the melting point). Furthermore QMS is naturally limited to certain kinds of isotopes. The goal of our studies in the last years was to find a new method to study atomic motion at the fundamental level which overcomes these limitations. Over the last years the relatively new technique of x-ray photon correlation was expanded by our group to work on the atomic scale. Measuring chemical fluctuations rather than self diffusion, this technique operates in the time regime and not in the energy regime. It is therefore possible to study systems at much lower temperatures with atomic scale x-ray photon correlation spectroscopy (aXPCS). It allows to investigate atomic scale diffusion in glasses well below glass transition temperatures and in the temperature range of intermetallic phases. The time resolution towards faster dynamics is only limited by the readout time of the detector and intensity of the x-ray beam and towards slower dynamics it is limited by the stability and the duration of the experiment. It is furthermore not restricted to certain elements, even though at the moment a high contrast between scattering elements under investigation is required due to today’s technical limitations at synchrotron sources.Fig. 1 Schematic setup of an aXPCS experiment Since the first successful aXPCS experiment was carried out only a few years ago [2], we continuously refined this method. One of the driving factors for a rapid progress of aXPCS was the fast improvement in the brilliance of synchrotron sources over the last years. This poster will compare results obtained for an Fe-Al system, measured both with QMS [1,3] and with aXPCS. Furthermore the challenges and drawbacks of both approaches will be discussed, e.g. the influence of short range order in the coherent method of aXPCS. This work was supported by the Austrian Science Fund (FWF): P22402. [1] G. Vogl and B. Sepiol, Acta Metall. Mater. 42 (1994) 3175.[2] M. Leitner, B. Sepiol, L.-M. Stadler, B. Pfau and G. Vogl, Nature Mat. 8 (2009) 717.[3] R. Weinkamer, P. Fratzl, B. Sepiol, and G. Vogl, Phys. Rev. B 59 (1999) 8622.
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