Photodesorption of NO from a metal surface: quantum dynamical implicationsof a two-mode model

Open-system density matrix theory is used to study the dissipative quantum dynamics of photoinduced, hot-electron mediated desorption of NO from Pt(11 1). Two electronic states are considered and both the DIET (Desorption Indu ced by Electronic Transitions) and DIMET (Desorption Induced by Multiple El ectronic Transitions) limits addressed. Besides the center-of-mass motion o f the molecule perpendicular to the surface plane, the vibrational motion o f the NO molecule is accounted for. In a first, methodological part the int errelations between various "direct" and "jumping wave packet" methods to s olve the underlying open-system Liouville-von Neumann equations of motion, are emphasized. In a second, applied part we investigate (i) the relevance of the popular "negative ion resonance" model, (ii) the role of coordinate- dependent electronic relaxation, and (iii) the implications of multiple-ele ctronic excitations. (C) 2000 Elsevier Science B.V. All rights reserved.