Completely inverted ClO vibrational distribution from OClO((2)A(2) 24,0,0)

The gas phase dissociation dynamics of symmetric chlorine dioxide highly ph otoexcited into its (2)A(2) 24,0,0 vibronic level has been investigated by monitoring both the kinetic energy release and the angular distribution of the O(P-3(2)) products via velocity map imaging. The resulting O(P-3(2)) ki netic energy profile provides full the vibrational distribution of the form ed ClO(X (2)Pi,upsilon) radicals. The measured O fragment kinetic energy di stribution reflects an unprecedented nonstatistical vibrational state popul ation of their diatomic partners, where the excess energy is focused only i n the three highest possible ClO vibrational levels upsilon = 18-20, with l ittle fragment rotation. The anisotropy of the dissociation process sheds n ew light on the fragmentation dynamics of this stratospherically relevant t riatomic molecule. (C) 2000 American Institute of Physics. [S0021-9606(00)0 0112-4].