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HL: Fachverband Halbleiterphysik

HL 61: Poster II: Materials, Interfaces and Heterostructures

HL 61.45: Poster

Donnerstag, 25. März 2010, 18:00–20:00, Poster D1

Recoil Effect in Light Element Materials: a Hard X-Ray High Kinetic Energy Photoelectron Spectroscopy Study — •Mihaela Gorgoi and Franz Schäfers — BESSY II, Helmholtz Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin

Recoil effects originate from a well defined transfer of momentum from the photoemitted electron to the atom, they cause energy shifts and broadening of the photoemission lines and they were first observed in gas phase photoemission [3]. In soft x-ray photoemission performed on solids this effect was negligible due to the small momentum of the photoelectron. However, in hard x-ray high kinetic energy photoelectron spectroscopy (HX-HIKE or HAXPES) the recoil effects can not be neglected any further since the photoemitted electron has a considerable and well defined amount of momentum [1,2]. In this work recent HX-HIKE investigations of highly oriented pyrolitic graphite (HOPG) and SiC are presented. Evidence of core level shifts as a function of excitation energy has been found in both cases. The energy shifts are assigned to the recoil effect. Nevertheless surprisingly the recoil energies recorded for both SiC and HOPG show a non linear behavior as a function of energy regardless of the orbital from where the photoelectron originates. The found trends will be discussed in the light of a theoretical approach. [1] Y. Takata et al., Phys. Rev. B 75 (2007) 233404. [2] M. Vos et al., Phys. Rev. B 78 (2008) 024301. [3] E. Kukk et al., Phys. Rev. Lett. 95 (2005) 133001.