Selectivity of bond-breaking in electron-induced dissociation of hydrocarbon films on Au surfaces

Electron-induced dissociation (EID) processes in organic and polymer films are important in a variety of applications. One scientific issue concerns the selectivity of low-energy electron bombardment to cleave a single C-H bond in hydrocarbon condensed films or adsorbed layers. We have undertaken combined TPD and FT-IRAS studies to identify and determine the purity of the surface species produced by EID of cyclohexane and benzene films on Au(111). Experimental evidence strongly supports a conclusion that EID of cyclohexane and benzene monolayer and multilayer films using incident electrons with an energy of 30 eV can be used to cleave a single C-H bond and produce a single chemisorbed product with high selectivity. An important consequence of these observations is that a variety of adsorbed hydrocarbon intermediates on Au(1 1 1) and other metal surfaces can be prepared in this manner, spectroscopically characterized, and used in studies to advance the understanding of chemical bonding, reactions and cata lysis at surfaces.