A photofragment spectrometer for studying photodissociation of molecules adsorbed on surfaces: The 257-nrn photolysis of cd₃1 on mgo(100)

A photofragment spectrometer has been developed to investigate the dissociation dynamics of molecules adsorbed on surfaces. State selective measurements of the internal and translational energy of photofragments ejected from the surface are carried out via multiphoton ionization (MPI) with mass and angle resolved time-of-flight detection. CD₃ radicals produced by the 257 nm photolysis of multilayer coverages of CD₃1 adsorbed on MgO (100) are formed primarily in v” = 0, similar to the distribution observed from photolysis of gas phase CD₃1. The translational energy distribution of the CD₃ fragment reflects the two dissociation pathways of methyl iodide, producing methyl in concert with both I*(²P_1/2) and I(²P_3/2). Investigations of the iodine fragment and a possible photolysis laser induced surface reaction are underway.