Charge models of disordered alloys for electron spectroscopy
- Event time: 1:00pm
- Event date: 22nd March 2010
- Speaker: Tom Underwood (Formerly School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
In a disordered alloy the positions of the atoms form an approximate crystal structure, but the type of atom located on each crystal site has some degree of randomness. Due to this, the atoms in disordered alloys exhibit a variety of local environments. E.g. for a binary disordered alloy consisting of atoms belonging to two elements A and B, the surroundings of any particular A atom could consist entirely of A atoms, entirely of B atoms, or a mixture of both. Since the properties of an atom are determined not only by which element it belongs to, but also by the nature of its surroundings, understanding how the electronic structure of an atom depends on its environment in alloys is vital for the atomic scale design of materials with desired properties. In this seminar I will use a phenomenological model to describe how an atom's local environment affects its electrostatic potential in various disordered alloys. These include alloys for which the amount of disorder depends on position – such as ultra-thin films which are partially destroyed due to heating. Knowledge of this is especially important for the interpretation of core-level X-ray photoelectron spectroscopy (CL-XPS) spectra. Since CL-XPS effectively measures the range of potentials present in a sample, knowing the relationship between potential and environment enables CL-XPS to non-destructively determine how atoms belonging to different elements are arranged. E.g. one could theoretically use CL-XPS in the future to determine the quality of embedded ultra-thin films.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..