PICOSECOND PHOTODISSOCIATION AND GEMINATE RADICAL RECOMBINATION IN ALKANE SOLUTIONS OF TETRAPHENYLHYDRAZINE

Tetraphenylhydrazine is observed to dissociate in less than 1 ps in alkane solution after 288 nm excitation. The diphenylaminyl radicals produced undergo rapid geminate recombination at a rate proportional to solvent shear viscosity. A strong magnetic field decreases the recombination yield. A model for the recombination is proposed which involves initial separation of nitrogen atoms and recombination of the radicals by rotational rather than translational motion alone. In a different approach the rates of radical recombination are also well described by Kramers' model of barrier crossing.