[1Ba01-09] Surface Science(SS3) Structure

[1Ba07] A feasibility study of RHEED as a method of subsurface hydrogen structure analysis

*Takaaki Kawamura^1,2, Shohei Ogura², Yuki Fukaya³, Takahiro Ozawa¹, Katsuyuki Fukutani^1,3 (1. Institute of Industrial Science, University of Tokyo, 2. School of Engineering, Tokyo Denki University, 3. Advanced Science Research Center, Japan Atomic Energy Agency)

Based on a multiple scattering calculation, we show that the position of a subsurface hydrogen can be determined by using RHEED. We take H absorption at Pd(100) as an example, since no definite position of subsurface H is reported so far. We assume that the H coverage is 1.5 ML; 1 ML of H are adsorbed at the hollow sites on the surface and 0.5 ML of H are absorbed below it. As the absorption sites, two very likely sites are considered. One is the octahedral (Oh) site and the other is the tetrahedral (Td) site. The rocking curves and the azimuthal plots from the two surfaces with absorbed H at Oh sites and those with absorbed H at Td sites are compared, showing large different variations with respect to H position under some H sensitive conditions, even when the effect of relaxations of Pd atoms down to 2 monolayers below the surface is considered. It can be concluded that the absorption sites are to be determined by using RHEED intensities under these conditions.