Kinetic energies of hydrogen atoms photodissociated from alkyl radicals

A series of alkyl halides was photodissociated at 205.1 nm, forming halogen atoms and alkyl radicals. The latter were in turn dissociated at the same wavelength into alkenes and hydrogen atoms. The average kinetic energies of the hydrogen atoms are large (1.5–2.0 eV) and decrease only slowly with increasing chain length. The inference is that the dissociation mechanism involves crossing from the Rydberg state surface to a repulsive region of the ground state surface at a point near the center of a C–C bond. As had been previously found by Koplitz and coworkers, isotope scrambling was seen in CH3CD2 radicals.