Reaction Dynamics of Electronically Excited Calcium Atom

Abstract

Absolute values of the total chemiluminescence cross-section for the beam-gas Ca(3P, 1D) + Cl4C → CaCl(A, B) + Cl3C and Ca(3P, 1D) + SF6 → CaF(A, B) + SF5 reactions have been measured at low collision energy, ET = 0.15 and 0.14eV, respectively. Both metastable atomic calcium states Ca(3P, 1D) were produced under low voltage dc-discharge conditions. By changing the discharge conditions, different metastable concentrations were produced to measure the state-to-state cross-section for both 3P and 1D reactions. The following values for the total chemiluminescence cross-sections were obtained:σD1 = 1.77 Å and σP3 = 0.25 Å for the Ca(3P, 1D) + Cl4C → CaCl(A, B) + Cl3C reaction.σD1 = 0.59 Å2 and σP3 = 0.56 Å2 for the Ca(3P, 1D) + SF6 → CaF(A) + SF5 reaction.σD1 = 0.04 Å2 and σP3 = 0.12 Å for the Ca(3P, 1D) + SF6 → CaF(B) + SF5 reaction.In addition, beam-beam experiments were carried out at the same average low collision energy that of the beam-gas, and therefore, normalization between both experiments was possible. This procedure allowed us to obtain the excitation function of the Ca(1D) + SF6 reaction in absolute values over the 0.15–0.60eV collision energy range.On the other hand, by simulation, the ratio of CaCl(B-X/A-X) emissions intensities was found to be of 0.15. The variation of this ratio with the relative concentration of 1D/3P in a Broida oven leads to the conclusion that this state favours the formation of the B state in the chemiluminescent Ca(3P, 1D) + CH3CHCl2 → CaCl(A, B) + CH3CHCl reaction.