ESD from NO and NO2 on Pt(100): Importance of Core-Level Assisted Ion Desorption and Application to the Investigation of NO2 Decomposition

Abstract

Core-level assisted electron stimulated desorption (ESD) as well as photon stimulated desorption (PSD) may give rise to significant contributions in the positive ion yield not only for ionically bonded adsorption systems /1/ but also for a number of covalently bonded molecules on metal surfaces /2–4/. Considering the short lifetime of an initially created core-hole (~ 10−16 sec) compared to the typical timescale of about 10−13 sec needed for the ion desorption, ion desorption is not expected to occur following core ionisation alone. Core-level assisted ESD is rather the result of secondary processes, either an Auger decay and/or a multielectron excitation in combination with the core-hole creation. Ion desorption will only occur if both conditions are fulfilled: the resulting electron holes are created in bonding orbitals (weakening of the bonding) and the lifetime of the complex is long enough /5/.