Electronic branching ratios in chemiluminescence from the collisions of Ca*(P-3(J), D-1(2)) atoms with halogenated methanes CX4-nYn (X, Y = F, Cl, Br)

Chemiluminescent reactions of calcium in the metastable P-3(J) and D-1(2) s tates with CFCl3, CFBr3, CCl2Br3, CCl3Br, and CFClBr2 molecules were studie d in a beam-gas arrangement. CaCl and CaBr spectra associated with the A(2) II-X(2)Sigma(+) and B(2)Sigma(+)-X(2)Sigma(+) transitions were observed, wh ile analogous emission from CaF was absent. The total collision cross-secti ons, chemiluminescence cross-sections and photon yields were measured. The photon yields are in a good agreement with statistical distribution based o n information theory approach when the CX3 product is treated as a nonlinea r rotor without vibrational excitation. (C) 2000 Elsevier Science B.V. All rights reserved.