The local structure of molecular reaction intermediates at surfaces.

A critical review is presented of the results of (experimental) quantitative structural studies of molecular reaction intermediates at surfaces; i.e. molecular species that do not exist naturally in the gas phase and, in most cases, are implicated in surface catalytic processes. A brief review of the main experimental methods that have contributed to this area is followed by a summary of the main results. Investigated species include: carboxylates, RCOO- (particularly formate, but also deprotonated amino acids); methoxy, CH3O-; carbonate, CO3; ethylidyne, CH3C-; NHx and SOx species; cyanide, CN. As far as possible in the limited range of systems studied, a few general trends are identified (108 references).