Thermal desorption and laser induced desorption of NO from adlayers of NO on diamond C(1 1 1)

Abstract

The processes of thermal desorption and photo-induced desorption were investigated for nitric oxide (NO) molecules from the adlayers on bare diamond C(1 1 1) (2×1) surface formed at 110 K. The surface coverage of NO was monitored by X-ray photoelectron spectroscopy (XPS). The kinetics of thermal desorption of NO was of first-order (the activation energy of desorption=9.8 kcal mol −1) at coverages below one monolayer, and of zeroth-order (9.2 kcal mol −1) for multilayer. Time-of-flight (TOF) detection of photo-induced desorption of NO was performed by laser beams of wavelengths 193, 248 and 308 nm. The photo-excitation that drives NO desorption was attributed to the band-gap excitation of substrate and/or surface for the NO coverages below one monolayer, and to the direct absorption by NO multilayer consisting of (NO) 2 species.