A gas phase scientist’s take on non-adiabatic processes at surfaces
Molecular Physics seminar
Monday 30 September 2013
to 11:00 at
Jerry LaRue (Stanford University)
The study of catalytic chemical reactions at surfaces (surface heterogeneous catalysis) is motivated both by the desire for fundamental understanding and the potential to use this understanding to create selective, low cost, and energy efficient surface reactions that utilize nontoxic catalysts. To gain insight into the processes behind these reactions, we studied the coupling between the vibrational degree of freedom of gas phase molecules and the electronic bath of a surface. Specifically, we measured the absolute probability and kinetic energy distributions of electrons emitted by colliding nitric oxide (NO) with a low work function metal surface. The vibrational states of NO were varied between v = 0 and 22 with incident translational energies ranging between 0.03 and 0.96 eV. We found two competing mechanisms for electron emission: Auger and vibrational autodetachment. These two mechanisms have different quantum yields for electron emission and translational energy dependence. These outcomes imply that important energy dissipation pathways involving non-adiabatic electronic excitations may play important roles in processes at surfaces.