Kinetics of the deactivation of I(52P1/2) by Br2. I. Quenching of excited iodine atoms

Abstract

The collisional deactivation of electronically excited iodine atoms, I(5²P_1/2), upon collision with Br₂ has been monitored using time‐resolved resonance absorption spectroscopy in the vacuum ultraviolet. The rate constant (at 295° K) characterizing the deactivation process was determined to be 5.6±0.2×10⁻¹¹ cm³ molecule⁻¹ sec⁻¹. Furthermore, the physical quenching of I(5²P_1/2) leading to formation of ground state iodine atoms, (I(5²P_3/2), was shown to play a monor role in the overall deactivation of the excited atom. This demonstrates the significance of the reaction I(5²P_1/2)+Br₂→IBr+Br(4²P_1/2,3/2) in the removal of the excited atoms upon collision with Br₂.