Journal of Physical Chemistry B, Vol.101, No.24, 4781-4786, 1997
Importance of Hydrocarbon Fragment Diffusion in the Formation of Adsorbed Alkyls via Eid of Multilayers on Pt(111)
The-interactions of low-energy electrons with organic solids is of interest for a variety of processes. One particular application that we are interested in has to do with using low-energy electron induced dissociation (EID) of hydrocarbon multilayers to prepare monolayer coverages of adsorbed hydrocarbon intermediates on reactive metal surfaces under UHV conditions. To probe the mechanism of the formation of adsorbed alkyl species via EID of multilayer alkane films, we have investigated EID in a two-component, structured multilayer system on Pt(111) at 90 K. Temperature-programmed desorption (TPD) was mainly used to study the reaction products of EID of films comprised of cyclohexane-d(12) and n-butane. On the basis of these results, we conclude that diffusion of the EID-produced alkyl fragments to the surface is the main channel for the formation of surface alkyl species in these types of systems. We exclude a dominant role for transfer of the alkyl fragment to the surface indirectly through abstraction of hydrogen atoms from molecules in the chemisorbed layer to produce new reactive fragments adjacent to the surface.
Keywords:ELECTRON-STIMULATED DESORPTION;SN/PT(111) SURFACE ALLOYS;LOW-ENERGY ELECTRONS;INDUCED CHEMISTRY;INDUCED DECOMPOSITION;INDUCED DISSOCIATION;AG(111);CYCLOHEXANE;ADSORPTION;BENZENE