Center for Functional Nanomaterials Seminar

Center for Functional Nanomaterials Seminar

Tuesday, April 22, 2008, 11:00 am
CFN Building 735 – Second Floor Seminar Room

Electron Dynamics at Surfaces
Pedro M. Echenique
Departamento de Física de Materiales, and Centro Mixto UPV/CSIC, and Donostia International Physics Center (DIPC), 20018 San Sebastian/Donostia, Basque Country, Spain
pedromiguel.echenique@ehu.es
http://dipc.ehu.es/echenique

Due to progress in experimental techniques and development of refined theoretical tools the study of the electron dynamics in solids is feasible. Interaction between lattice, electron, and spin subsystems as well as interaction within each of these subsystems is crucial to understand the mechanism of single-particle excitation dynamics, i.e. the lifetime of excitations. The lifetime sets the duration of the excitation and in combination with the velocity determines the mean free path, a measure of the influence of the excitation. Interest on the study of particle dynamics is motivated by the important role that excited electrons and holes play in many processes, e.g. in energy, charge, and spin transport in bulk materials, at surfaces, across interfaces, and at nanosystems.
In this presentation theoretical and experimental results on electron dynamics are discussed in terms of different decay mechanisms for bulk electronic states, surface and image states on metal surfaces. We will concentrate mainly in the electron-electron inelastic decay mechanism, and in electron transfer from single adatoms to surfaces.
We will also show that, in contrast to earlier expectations, a low energy collective electronic excitation mode can be found on bare metal surfaces. This mode has an acoustic (linear) dispersion and it has been observed for the first time on Be(0001) but has a very general character and should be present on many metal surfaces.
Host: Emilio Mendez