EXAFS and Near Edge Structure IV

J. Phys. Colloques 47 (1986) C8-179-C8-183
DOI: 10.1051/jphyscol:1986833

THE USE OF PHOTON STIMULATED ION DESORPTION SEXAFS IN THE DETERMINATION OF SURFACE STRUCTURE

G. THORNTON¹, D.R. WARBURTON², I.W. OWEN³, C.H. RICHARDSON⁴, R. McGRATH⁵, I.T. McGOVERN⁵ et D. NORMAN<sup>1

1</sup>  Also at Science and Engineering Research Council, Daresbury Laboratory, GB-Warrington WA4 4AD, Great-Britain
²  Chemistry Department, Manchester University, GB-Manchester, M13 9PL, Great-Britain
³  Vacuum Generators Ltd. Menzies Road, GB-Hastings TN34 1YQ, East Sussex, Great-Britain
⁴  V.G. Scientific Ltd, The Birches Industrial Estate, Imberhorne Lane, GB-East Grinstead RH19 1UB, West Sussex, Great-Britain
⁵  Department of Pure and Applied Physics, Trinity College, Dublin 2, Ireland

Abstract
Two studies of photon stimulated ion desorption are described. Both involved the study of dissociative H₂O adsorption, the substrates being stepped SrTiO₃ (100), and Si(100). In the case of the Si(100) substrate, a direct PSID mechanism dominates the H⁺ yield at the Si K-edge allowing important structural information to be determined from the SEXAFS. In contrast, only bulk information is obtained from the SrTiO₃(100) ion yield at the Sr L₁ and Ti K edges because a non-local mechanism of ion desorption dominates. The most likely reason for this difference in behaviour is related to the positions of lower-energy substrate absorption edges.