EVIDENCE FOR THE ROLE OF SURFACE TRANSIENTS AND PRECURSOR STATES IN DETERMINING MOLECULAR PATHWAYS IN SURFACE-REACTIONS

Dynamic studies of the coadsorption of molecules at low temperatures using photoelectron and vibrational spectroscopies provide an insight to the molecular behaviour of coadsorbates. A number of metal-gas systems are discussed where the evidence indicates the participation of such transients as O-(s) and O2-(s) in determining reaction pathways. It is shown that precursor states present at immeasurably small surface concentrations can provide low energy channels to chemisorbed products when both reactants are short-lived surface transients. Support for the mechanism also comes from computer-modelling studies.