Seminars Archive

ALOISA recent advances: applications of Resonant Photoelectron Diffraction

Abstract
The Photoelectron Diffraction (PED) and Resonant Photoemission (RESPES) measurements have been increasingly employed to investigate surface properties at the ALOISA beamline in the recent years. PED is a structural technique that permits to probe the local atomic arrangement around a chemically selected emitter. RESPES is a spectroscopic technique that can provide insight into the contributions of different atomic species to the electronic states in the valence/conduction region by selective enhancement of their intensity upon fine tuning of the photon energy across the ionization threshold of a specific element. The combination of these two techniques (RESPED) makes possible to study the structure in those systems where the resonant effect can greatly enhance the signal with respect to the usual photoemission one. Most importantly, beyond the element selectivity of conventional PED, RESPED offers the possibility to discriminate between atoms of the same species but differing in their valence state and/or structural environment. Therefore RESPED can be used to study certain problems hitherto unaccessible to conventional structural techniques. Hereafter, we will review a few case studies that are representative of the different target applications offered by the RESPED technique, namely the dilution of Mn atoms in CdTe(110), [1] the Fe oxidation states in Fe3O4(111), [2] and the atomic localization of the Defect state in TiO2(110) [ 3,4]. [1] L. Sangaletti et al. Phys. Rev. B 81 (2010) 245320. [2] H. Magnan et al. Phys. Rev. B 81 (2010) 085121. [3] P. Krueger et al. Phys. Rev. Lett. 100 (2008) 055501. [4] P. Krueger et al. Phys. Rev. Lett. 108 (2012) 126803.