A number of mechanisms have been identified for explaining recent experimental results of photon-induced chemistry of molecules adsorbed on surfaces of metals, semiconductors, and insulators. The initial step of these mechanisms invariably involves excitation of either the adsorbate or the substrate. Two illustrative systems, NO and Mo(C0)6 on Si(111)7x7, will be discussed. The desorption and dissociation of NO are found to occur via interaction of photogenerated holes with the NO - substrate complex. In contrast, photoelectronic excitation of Mo(CO)6 leads to the detachment of the CO ligands. However, a new photochemical pathway involving electron dissociative attachment is opened when Mo(C0)6 is coadsorbed with K on Si.
W. Ho, W. Ho,
"Nonthermal Photon-Assisted Chemistry Of Oriented Molecules On Solid Surfaces", Proc. SPIE 1056, Photochemistry in Thin Films, (15 August 1989); doi: 10.1117/12.951629; https://doi.org/10.1117/12.951629