Ultraviolet Photodissociation of Molecular Beams.

The Ar-F laser 193 nm was used to photodissociate molecular beams of SO2, CS2, aryl halides, phenyl cyanide and isocyanide, nitroalkenes and nitrobenzene, and H2O2. The translational energy distributions of the fragments were measured. In addition, the internal energy distributions of CS from CS2 and OH fragments from H2O2 were measured. The excess of photon energy over bond energy is released primarily as vibration for SO2 and primarily as translation for H2O2. For CS2 comparable amounts of energy appear in translation and vibration 80 of the S atoms appear in the 1D state. Both phenylcyanide, C6H5CN and phenylisocyanide, C6H5NC gave CN and C6H5 fragments. In spite of the greater energy available, C6H5NC yielded slower CN fragments. The iodobenzene fragmentation occurred by two processes, one from the initially excited state which gave fast fragments and the other from a lower energy state which gave slower fragments and, of course, more internal energy. Author