Photodissociation of CBrCl3 at 234 and 265 nm:: Evidence of the curve crossing

The photodissociation dynamics of CBrCl3 was studied near 234 and 265 nm using a two-dimensional photofragment ion imaging technique. Bromine fragments monitored in this study were produced via direct dissociation of CBrCl3, represented by CBrCl3--> CCl3+Br(P-2(1/2))/Br(P-2(3/2)). The branching ratio of Br(P-2(1/2)) (denoted Br*)/Br(P-2(3/2)) (denoted Br) showed strong excitation energy dependence. The product quantum yields at two different excitation wavelengths were Phi (234 nm)(Br*)=0.31 +/- 0.01 and Phi (265 nm)(Br*)=0.68 +/- 0.02, respectively. The speed and angular distributions of Br* and Br fragments were determined. Similar values of beta(234 nm)=-0.44 and beta(265 nm)=-0.47 for Br were observed, while beta values for Br-* were found to be markedly different, beta(234 nm)=-0.34 and beta(265 nm)=1.43. The strong curve crossing, (1)Q(1)-->(3)Q(0), and the angular distribution of Br* suggesting a typical perpendicular transition, were observed at 234 nm photodissociation. (C) 1999 American Institute of Physics. [S0021-9606(99)02533-7].