Investigation of beam-induced dynamics in oxide glasses via aXPCS

Autor(en)

Michael Legenstein, Bogdan Sepiol

Abstrakt

Investigating diffusion in solid state matter has been a long-standing challenge. In recent years a new technique called atomic-scale X-ray Photon Correlation Spectroscopy (aXPCS) has emerged.
Its working principle is the same as for the long established Dynamic Light scattering, but with X-rays
instead of visible light. The successful realization of an aXPCS experiment was made possible by
powerful new X-rays sources like third-generation synchrotrons and free-electron lasers.
Ideally, the X-ray beam would only measure internal dynamics and leave the system unperturbed
otherwise. However, a recent study has shown that the dynamics in vitreous silica and germanium,
measured via aXPCS is proportional to the flux of the beam, while the dynamics in metallic glasses
and single-crystalline Cu90Au10 does not show this behaviour. This indicates that aXPCS does
not only probe dynamics in some materials like oxide glasses, but also induces dynamics. Further
investigations of this beam-induced dynamics will be the focus of this thesis.
The thesis begins with a theoretical treatment of aXPCS as well as network glasses in general
and oxide glasses in particular. Then the experimental approach and the data evaluation process
will be presented in detail.
In the main part the effects of the beam on the dynamics of a wide range of oxide glasses will be
investigated. It will be shown that the dynamics in all glasses show a dependence on the photon flux.
The dynamics measured at room temperature is proportional to the flux in all glasses, indicating
that the dynamics is entirely beam-induced. At temperatures well above room temperature the
influence of the beam becomes significantly smaller, hinting at a mixture of beam-induced and
internal dynamics.
Furthermore, the characteristics of the induced dynamics will be explored in detail. Finally, the
consequences of beam-induced dynamics on future aXPCS experiments will be discussed and some
possible mechanism underlying beam-induced dynamics presented.

Organisation(en)

Dynamik Kondensierter Systeme

Anzahl der Seiten

63

Publikationsdatum

02-2018

ÖFOS 2012

103008 Experimentalphysik, 103009 Festkörperphysik, 103015 Kondensierte Materie, 103018 Materialphysik

Schlagwörter

ASJC Scopus Sachgebiete

Condensed Matter Physics

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/investigation-of-beaminduced-dynamics-in-oxide-glasses-via-axpcs(b247916d-90a3-41fc-8f05-10bf6d4ef4be).html