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J. Phys. Condens. Matter 13 (2001) pp. L607-L612

Reflection anisotropy spectroscopy of W(110): an optical probe of surface electronic structure

D. S. Martin, O. Zeybek, B. Sheridan, S.D. Barrett and P. Weightman

Surface Science Research Centre, The University of Liverpool, PO Box 147, Liverpool, L69 3BX, UK

J.E. Inglesfield

Department of Physics and Astronomy, University of Wales Cardiff, P.O. Box 913, Cardiff, CF2 3YB, United Kingdom

S. Crampin

Department of Physics, University of Bath, BA2 7AY, United Kingdom

Abstract
The reflection anisotropy (RA) spectrum of W(110) has been measured, showing a large resonance feature which is due to transitions from occupied surface states. To understand the origin of the spectral profile a layer-KKR calculation of the surface electronic structure has been performed and from the joint density of states the important transitions have been identified. These are due to transitions from surface states with a large p-component to unoccupied d-states, the anisotropy arising from the relative weight of p_x and p_y. These surface states have been previously measured in angle-resolved photoemission. The adsorption of oxygen on the W(110) surface has been studied, showing a decrease in anisotropy with increasing O coverage and confirming the surface sensitivity. For the first time the consideration of the density of states upon the initial and final electronic states participating in RA transitions is made.