Vibrational relaxation and photochemistry of HCl(v=1,2) and Br atoms

A laser-excited fluorescence method is used to measure the total deactivation rates of HCl(v=1) and (v=2) by Br atoms. The rate constant for v=1 is (2.8±0.52) ×10−13 cm3 molecule−1 sec−1 (295 °K) and for v=2 is (1.8±0.33) ×10−12 cm3 molecule−1 sec−1 (294 °K) The deactivation of HCl(v=1) by Br occurs through V→T,R energy transfer, while the deactivation of HCl(v=2) is believed to occur largely by reaction. The rate constant for deactivation of HCl(v=1) by Br2 is (3.26±0.13) ×10−14 cm3 molecule−1 sec−1 (295 °K). The reaction between HCl(v=2) and Br is discussed as a possible means of separating Cl isotopes by vibrational photochemistry.