PYRAZINE - SUPERCOLLISIONS OR SIMPLE REACTIONS

Photodissociation of 1,4 diazine (pyrazine) following 248 nm (S-2<--S-0) and 308 nm (S-1<--S-0) excitation has been studied by photofragment translational spectroscopy. While the latter wavelength was inefficient at generating reactive products, the former wavelength afforded a rich variety of fragments, the most translationally energetic being HCN carrying up to 36 kcal/mol. The implications of this reactive mechanism toward interpretation of vibrational energy transfer experiments from hot ground state pyrazine are considered. The absolute quantum yields phi(248 nm, 27-A)=0.40+/-0.10, phi(248 nm, 27-B)=0.08+/-.02, phi(308 nm, 27-B')=0.003+/-.001 and the two corresponding translational energy distributions are presented. (C) 1995 American Institute of Physics.