Journal of Physical Chemistry, Vol.99, No.44, 16307-16314, 1995
Ion Imaging of the Photodissociation of OCS Near 217 and 230 nm
OCS was photodissociated near 217 and 230 nm, and the resulting CO was probed by 2 + 1 resonant multiphoton ionization (REMPI) using the B-1 Sigma(+), C-1 Sigma(+) <--<-- X(1) Sigma(+) transitions. The CO+ was detected by the ion imaging technique of Chandler and Houston. The nascent CO was found only in the v = 0 state, and its rotational state population distribution was bimodal. It is remarkable that this CO rotational distribution has no tail extending to states of lower J. beta values rise monotonically with J. Recent potential energy surface calculations by Rokutan et al. provide reasonable explanations for the results : (1) dissociation can take place from near degenerate A " and A’ states, each of which generates a different CO product distribution; (2) a molecule excited by the initial absorption to an A’ state can cross over in linear geometry at two different C-S distances to dissociating states.