Anomalous branching ratio in the femtosecond surface chemistry of O₂/Pd(111)

In this paper we examine the surface chemistry of O2/Pd(111) under conditions of dense electronic excitation generated by femtosecond laser pulses. In contrast to the cases of conventional photo-activation and thermal activation, with femtosecond excitation the branching ratio for desorption/dissociation is found to favor desorption strongly. The results are discussed in terms of a recently developed model for desorption induced by multiple electronic transitions (DIMET).