Vibrationally excited molecules from the reaction of H atoms and chemisorbed H atoms on a metal surface

The vibrational excitation of H2 produced in the reaction between gas-phase and chemisorbed H atoms on a tungsten surface is studied by use of classical trajectory procedures. In small and intermediate-impact parameter (b) collisions, the reaction probability P(b) is large, and a major fraction of the available energy goes into vibrational excitation of H2. Gas atoms approaching the surface with b close to the H2 bond distance are particularly efficient in H2 formation. In large, b collisions, both P(b) and vibrational excitation are inefficient. Such a decrease in P(b) and vibrational excitation with increasing b produces a population inversion. The reaction dynamics and distribution of reaction times are discussed in detail.