State resolved detection of Cl, Br, CIO and BrO

Abstract

Nascent CIO and BrO products in photodissociation or reaction processes were observed in a state resolved manner by applying the two-photon laser-induced fluorescence technique, where two simultaneously absorbed laser photons excite the products to the C-state. CI and Br atoms can be observed by means of three-photon excitation with subsequent recording of the VUV fluorescence light. The advantage of this detection technique, other than the simpler laser system, is the use of low energy photons which don't interfere with other processes. State resolved detection of BrO products has been performed in the reactions 0(1D)+CF3Br and Br+03.The photodissociation of OCl0(2A2v1,v2,v3)→Cl0(X2πω, v,J,λ)+0(3P) in the 356–371 nm region is clearly a function of the initial type of motion of OC10(2A2vl,v2,v3). The population of the fragment rotational levels is observed to resemble Boltzmann distributions of around 1000 K. When high vibrationally excited states of the symmetric stretch mode of OC10(2A2v1>17,v2,v3) are excited, then most of the available energy is transferred to CIO vibration. Those extremely vibrationally excited CIO products carry sufficient energy to react with ambient nitrogen in the atmosphere, which is confirmed in a final end product analysis where the formation of N20 is observed.The Cl quantum yield of the minor OCIO(2A2 v1,v2,v3) → CI(2PJ) + 02 channel depends on the state of the parent molecule and is of the order of 4%.