Branching ratios into the electronic states BaCl(A(2)Pi(1/2), A(2)Pi(3/2),B-2 Sigma(+)) from the reactions of Ba[6s5d(D-3(J))] with CF3Cl and CF2Cl2following the pulsed dye-laser excitation of atomic barium

Branching ratios into the electronic states BaCl(A(2)Pi(1/2,3/2), B(2)Sigma (+)) are investigated following the collisions of Ba[6s5d(D-3(J))], 1.151 e V above the 6s(2)(S-1(0)) ground state, in the presence of CF3Cl and of CF2 Cl2 where these molecular states are thermodynamically accessible on collis ion. Ba(D-3(J)) is produced following the initial pulsed dye-laser excitati on of atomic barium via the allowed transition at lambda = 553.5 nm {Ba[6s6 p(P-1(1))] <-- Ba[6s(2)(S-1(0))]} in excess helium buffer gas at 900 K, and this optically metastable state is then generated in the 'long-time domain ' by a combination of radiative and collisional processes. Ba(D-3(J)) is th en monitored principally by the spectroscopic atomic emission marker transi tion at lambda = 791.1 nm {Ba[6s6p(P-3(1))] ---> Ba[6s(2)(S-1(0))]} where B a(P-3(1)) results from collisional activation of Ba(D-3(J)). In the presenc e of CF3Cl and CF2Cl2, the following long wavelength molecular chemilumines cence transitions of BaCl are also monitored as a function of time: BaCl(A( 2)Pi(1/2) ---> X(2)Sigma(+), lambda = 966 nm, Delta v = 0), BaCl(A(2)Pi(3/2 ) ---> X(2)Sigma(+), lambda = 910 nm, Delta v = 0) and BaCl(B(2)Sigma(+) -- -> X(2)Sigma(+), lambda = 843 nm, Delta v = 0). A kinetic analysis employin g both the integrated intensities of the atomic emission and these long wav elength emissions, coupled with optical sensitivity calibrations, yields br anching ratios in the BaCl(A(2)Pi(1/2,3/2), B(2)Sigma(+)) states from the t wo reactants. These are found to be as follows: (I) CF3Cl: BaCl(A(2)Pi(1/2) ) 4.4 +/- 1.2 %, BaCl(A(2)Pi(3/2)) 0.097 +/- 0.019 %, BaCl(B(2)Sigma(+)) 0. 026 +/- 0.013 %; (II) CF2Cl2: BaCl(A(2)Pi(1/2)) 1.7 +/- 0.4 %, BaCl(A(2)Pi( 3/2)) 0.084 +/- 0.023 %, BaCl(B(2)Sigma(+)) 0.031 +/- 0.009 %. The logarith mic variation of these branching ratios with the energies of the states is essentially Boltzmann in character in both cases, as found hitherto with ot her halogenated targets with which the present results are compared, with a n effective temperature close to the ambient temperature of the measurement s.