Determination of branching ratios in a kinetic investigation of the atomicresonance fluorescence and molecular chemiluminescence, CaCl(A(2)Pi(1/2, 3/2,) B-2 Sigma(+) -> X-2 Sigma(+)), resulting from the reaction of Ca[4s4p(P-3(J))] with Ch(3)Cl following pulsed dye laser excitation of atomic calcium

Measurements in the time-domain of molecular chemiluminescence from CaCl(A( 2)Pi (1/2), A(2)Pi (3/2). B(2)Sigma (+) -->X(2)Sigma (+)) and atomic resona nce fluorescence from Ca(4(3)P(1) --> 4(1)S(0)) have been made in order to determine electronic branching ratios to yield CaCl(A(1/2), A(3/2). B) foll owing the Cl-atom abstraction reaction of electronically excited calcium at oms, Ca[4s4p(P-3(J))], 1.888 eV above the 4s(2)(S-1(0)) ground state, with CH3Cl. Ca[4s4p(P-3(1))] was generated by the pulsed dye-laser excitation of ground state calcium atoms at lambda = 657.3 nm {Ca[4s4p(P-3(1))] <-- Ca[4 s(2)(S-1(0))]} at elevated temperatures in the presence of CH3Cl and excess helium buffer gas in a slow flow system, kinetically equivalent to a stati c system. Atomic and molecular emissions were recorded following rapid Bolt zmann equilibration within the Ca(4(3)P(0,1,2)) spin-orbit manifold, atomic emission being restricted to the P-3(1) state as the P-3(0) and P-3(2) sta tes are long-lived, being so called 'reservoir states'. Atomic fluorescence emission profiles at the resonance wavelength together with the molecular chemiluminescence emissions CaCl(A(2)<Pi>(1/2) --> X(2)Sigma (+), Deltav = 0, lambda = 621 nm), CaCl(A(2)Pi (3/2) --> X(2)Sigma (+), Deltav = 0, lambd a = 618 nm) and CaCl(B(2)Sigma (+) --> X(2)Sigma (+), Deltav=0, lambda = 59 3 nm) were recorded. The atomic and molecular emissions demonstrated expone ntial decays characterised by decay coefficients which were equal under ide ntical chemical conditions thus demonstrating the production of CaCl(A(2)Pi (1/2),(3/2), B(2)Sigma (+)) by direct reaction of Ca(P-3(J)) with CH3Cl. T he combination of the time-dependences of the atomic and molecular profiles as a function of the concentration of CH3Cl together with the integrated a tomic and molecular intensities, placed on a common intensity scale by cali bration of the optical system against a spectral radiometer, yielded branch ing ratios into the A(2)Pi (1/2), A(2)Pi (3/2) and B(2)Sigma (+) states of CaCl. These were found to be as follows: A(1/) 2 (2.6 +/- 1.1) x 10(-3); A( 3/2) (1.9 +/- 0.8) x 10(-3) and B (3.6 +/- 2.0) x 10(-4). To the best of ou r knowledge, these data represent the first measurements of electronic bran ching ratios of calcium chlorides into specific molecular states for reacti ons of Ca(4(3)P(J)) determined in the time-domain. The results are compared with various related data for total branching ratios into electronic state s studied in the single collision condition for this atomic state with CH3C l using molecular beams. These are also compared with branching ratios of S rCl(A(2)Pi (1/2), A(2)Pi (3/2), B(2)Sigma (+)) following the reaction of Sr [Ss5p(P-3(J))]+ CH2Cl2 investigated following pulsed dye-laser excitation w here the yields of SrCl(A(1/2), A(3/2), B) were of similar low magnitudes.