Laser induced fluorescence studies of the reactions of barium (1S, 3D) and strontium (1S, 3P) with halogenated methanes

Abstract

Laser excitation of barium and strontium atoms followed by laser induced fluorescence detection of chemical reaction products is used to study the dynamics of reactive collisions of these reagents with halogenated methanes. We report state-to-state distributions in reactions of ground state Ba and ground state Sr, (1S0), and laser excited Ba(3D2 and 3D1) and Sr(3P1) with CH3X, CF3X (X=F,Cl,Br), CCl3F, and CCl4. We demonstrate that in certain cases reaction can be initiated by electronic excitation of the atomic reagent. We also show that the vibrational energy distribution of the diatomic alkaline earth halide product is in each case determined principally by the nature of the reacting halogenated methane irrespective of the surface on which the reaction is initiated. Measurements of the relative reactivity of different spin orbit states of excited barium are also presented.