Regensburg 1998 – wissenschaftliches Programm

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O: Oberflächenphysik

O 29: Struktur und Dynamik reiner Oberfl
ächen (I)

O 29.4: Vortrag

Donnerstag, 26. März 1998, 12:00–12:15, H44

Zero-order photoelectron diffraction as contrast mechanism in Auger and photoelectron microscopy — •M. Zharnikov, M. Neuber, and M. Grunze — Angewandte Physikalische Chemie, Universit"at Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg

An applicability of photoelectron diffraction as a contrast mechanism in Auger- and photoelectron microscopy is considered by using Ni polycrystal as a test system. Whereas some contrast can be expected at a particular kinetic energy of electrons, kinetic energies where the zero-order interference or forward focusing dominates over other scattering events are preferable because of the pronounced strength of forward scattering and direct correlation between photoelectron intensity and the orientation of the interatomic axis in the sample. Well-resolved images of individual microcrystallites on the surface of Ni polycrystal have been obtained by using the Ni 2p_3/2 photoelectrons (E_kin = 635 eV) collected at a widely variable emission direction. Even some crystallites, which were not distinguished by an optical microscope, have been easily discriminated by the photoelectron diffraction contrast which amounted almost 50 % of the whole intensity scale and could be observed directly during acquisition of the images. A crystallographic information on the orientation of the microcrystallites constituting the polycrystal was obtained. An approximate identification of the crystallographic orientation of several individual microcrystallites in the investigated Ni polycrystal has been achieved.