Shin-ichi Ishi

AN OVERVIEW ON THE ELECTRONIC AND VIBRATIONAL PROPERTIES OF ADSORBED CO

This paper addresses itself to the question of the inadequacy of the donation-backdonation model for treating CO adsorption (both strong and weak) especially in the lihght of recent measurements by ARUPS, I-UPS, HREELS and NEXAFS to identify the 2 pie level with or without occupancy The variation, including the sign (decrease or increase) of the work functson as a result of CO adsorption, is ldenufied to be due to the reversal or change in magnitude of polarity of the molecule in the adsorbed state. The reversal of the ordenng of the valence states according to thus model becomes a natural consequence of the relaxation of the equlibrium internuclear d-stance. The systematlcs in the adsorption super-structures and the variation of other adsorption parameters especially that of adsorption energy are considered for both group VIII and I b metals. The characteristics of the vibrational properties of adsorbed CO on group VIII and Ib metals are considered in terms of the electronic properties with a vtew to obtain possible correlations in the future. The need for more accurate measurements to evaluate the 5sigma-1pie separation in the adsorbed state is indicated, which will enable. It is hoped a synthesls to be made of a unified correlation between internuclear distance, wave number of (C-O) and delta(5sigma-lpie) within a single framework model The charactensitcs of nitrogen 0soelectronsc with CO) adsorption on group VIII metals are also considered for comparison

Adsorption of xenon atoms on metal surfaces

Abstract In recent times the adsorption of rare gases, especially xenon, on metal surfaces has been extensively used to rationalize certain basic features of the adsorption process. Available experimental data on the energetics of adsorption and other photoelectron spectroscopic measurements show that a chemical bonding model alone can explain adequately all the results reported in the literature. Detailed theoretical models have been developed to rationalize the features observed in photoelectron spectra.

Assignments in the UPS of Xe atoms on metals

Donnees theoriques et numeriques relatives aux atomes de Xe adsorbes sur divers metaux (Pt, Ir, Pd, W, Fe, Ni, Cu)

NMR of Xe Adsorbed on Graphite

The NMR of 129Xe adsorbed on exfoliated graphite was observed in three different adsorbed phases: multilayer, 2D (two-dimensional) solid and 2D liquid phases. The chemical shifts observed with the 2D solid and the 2D liquid were much greater than those with the respective 3D phases, which may be attributed to Xe-graphite interactions. The difference in the shift between the two 2D phases was found to be of the same order of magnitude as in the 3D Xe. When the chemical shift in the multiayer phase is compared with that in 3D Xe, the multilayer phase seems to lie between the 3D solid and 3D liquid with respect to atomic density.

Theory of angular and speed distributions of desorbed hydrogen from metal surfaces

Abstract A quantum theoretical approach for angular and speed distributions of recombinatively desorbed D2 from metal surfaces is proposed. The complex D‡2 is activated on the saddle point of the three-dimensional potential surface with respect to its center-of-mass coordinate and vibrates with frequencies v‡2 parallel to the metal surface. Through the interface of the metal with the vacuum these two vibration modes are coupled with translational motion along the reaction path and lead to a transmission coefficient in which momentum representation of the vibrational wave function enters. Angle-resolved speed distributions of the desorption rate are calculated on the basis of Eyrings theory of rate processes, incorporated with quantum mechanical effects. Theoretical predictions reproduce very well a variety of the characteristic features of the experimental results.

UPS from adsorbed Hg on metal surfaces

Abstract The assignments for UPS from adsorbed mercury on metal surfaces are discussed by means of the molecular orbital description which reveals the characteristic features observed by Egelhoff et al. [Surface Sci. 54 (1976) 670] in the region of 8–10 eV below the Fermi level.