Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 47: Focussed Session: Frontiers of Electronic Structure Theory - Non-equilibrium Phenomena at the Nano-scale IV

O 47.5: Vortrag

Mittwoch, 2. April 2014, 11:45–12:00, TRE Ma

Photoelectron driven plasmaron excitations in (2x2)K/Graphite — •Bo Hellsing — Department of Physics, Gothenburg University, Sweden

A new type of plasmarons formed by the compound of photoelec- trons and acoustic surface plasmon (ASP) excitations is investigated in the system p(2 * 2)-K/Graphite. The physics behind these types of plasmarons, e-plasmarons, is different from the ones re- cently found in graphene and quantum well systems, where the loss features results from the photohole-plasmon interaction in the material, h-plasmarons. Based on the first principles scheme, Time dependent density functional (TDDFT), we calculated the linear response due to the presence of the escaping photo-electron and determine the ASP dispersion. The coupling between the photoelectron and the ASP gives rise to excitation of the e- plasmarons manifested by a broad dispersive feature shifted about 0.5 eV below parabolic K induced quantum well band (QWB) in agreement with the ARPES experiment by Agdal et al. The e-plasmarons should be considered as a source of the loss satellite structure in ARPES for 2D systems. In addition they are important to take into account in theoretical studies of different compounds as they reflect an additional channel for excitations of plasmons. This could then increase the photon-plasmon conversion yield which obviously is of interest in the field of plasmonics.