Regensburg 2004 – wissenschaftliches Programm

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M: Metallphysik

M 5: Elektronische Eigenschaften

M 5.3: Vortrag

Montag, 8. März 2004, 12:15–12:30, H4

Initial and final state band contributions in angle resolved photoemission spectra of Bi(111) — •Christian Ast^1,2 and Hartmut Höchst¹ — ¹Synchrotron Radiation Center, University of Wisconsin-Madison, Stoughton, WI, USA — ²Max-Planck-Institut für Festkörperforschung, Stuttgart

Establishing the bulk valence band dispersion E_i(k) from angle resolved photoemission spectra is still an ongoing challenge since the final state bands E_f(k) are generally not known. However, using a broad range of photon energies the measurements extend over several bulk Brillouin zones which can then be used to extract information about the valence band states. An analysis is presented in which the final and initial state dispersion along ΓT is extracted from photoemission spectra of Bi(111). We will show that the free electron final state (FEFS) model is valid above 60 eV. For lower photon energies, we establish an energy dependent extension of the FEFS’s. Because of direct and umklapp transitions into multiple final states we observe emission gaps indicating avoided crossings in certain branches of the final state bands. Once the origin of these additional features is identified, the true bulk valence band dispersion can be established.