Role of Surface Temperature in the Precursor-Mediated Dissociative Chemisorption of ${\mathrm{N}}_2$ on W(100)

Molecular-beam techniques have been used to probe the dynamical origin of the surface-temperature ($T_s$) dependence of the precursor-mediated dissociative chemisorption of ${\mathrm{N}}_2$ on W(100). Measurements of the angular and velocity distributions of scattered molecules have revealed that increasing $T_s$ primarily serves to reduce the fraction of precursor molecules that go on to dissociate, by biasing the kinetics in favor of desorption. In contrast, the trapping probability into the precursor state is found to be relatively insensitive to this parameter, accounting for ≲20% of the observed effects.