Reactions of Metal Atoms. I. The Combination of Mercury and Chlorine Atoms and the Dimerization of HgCl

The combination reaction of mercury atoms with chlorine atoms from the mercury-sensitized flash photolysis of CF3Cl has been studied. The kinetics were followed by monitoring the band intensities of the Π1/22←2Σ and2Π3/2←2Σ systems of the HgCl transient with kinetic absorption spectroscopy. The absorption spectrum agrees well with the previously reported emission spectrum. The extinction coefficient for the 2790-Å band of the Π1/22−2Σ system has been measured to have the value of 1.6 ± 0.6 × 105M−1·cm−1. The second-order rate constant for the reaction is 3 and 0.9 × 1010M−1·sec−1 in 720 torr CF3Cl and 10 torr CF3Cl + 710 torr Ar, respectively, and is independent of temperature between 110° and 170°. The rate constant for the dimerization of HgCl is 3.0 ± 1.8 and 1.9 ± 1.3 × 1011M−1·sec−1 in the above mixtures. The reaction is second order in [HgCl].