Interpretations of the mercury halide (B 2Σ+–X 2Σ+) chemiluminescence from reactive quenching of Hg(3P2) by halogen containing molecules

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Abstract
The HgX(B 2Σ+–X 2Σ+), X=halogen, emission spectra have been recorded from Hg(3P2) atom reactions with several halogen containing molecules using a flowing afterglow reactor. The HgX* emission intensities were compared with the HgCl* emission intensity from Hg(3P2)+Cl2 to assign rate constants for HgX(B) formation. The Hg(3P2)+ diatomic halogen reactions have large kHgX* and their branching fractions for HgX(B) formation are probably unity. The polyatomic reagents generally gave much smaller kHgX*; although, a few moderately good donors, e.g., CF3I, CBr4, CCl4, and NF3 were identified. The experimental spectra were numerically simulated to assign HgX(B) vibrational energy distributions. A decrease in 〈fV(HgX)〉 was found for the Cl2, Br2, I2 series which is analogous to previous findings for 〈fV(XeX)〉 from reactive quenching of Xe(3P2). Possible reasons for the similarity are discussed. The HgX(B) vibrational energy disposal for polyatomic reagents is compared to analogous data for reactions of alkaline earth metal atoms and Xe(3P2).