Vibrational relaxation of O3(ν2) by O((3)P).

Abstract

Laboratory measurements of the rate coefficient for quenching of O3(ν2) by ground-state atomic oxygen, kO(ν2), at room temperature are presented. kO(ν2) is currently not well known and is necessary for appropriate nonlocal thermodynamic equilibrium modeling of the upper mesosphere and lower thermosphere. In this work, a 266 nm laser pulse photolyzes a small amount of O3 in a slow-flowing gas mixture of O3, Xe, and Ar. This process simultaneously produces atomic oxygen and increases the temperature of the gas mixture slightly, thereby increasing the population in the O3(ν2) state. Transient diode laser absorption spectroscopy is used to monitor the populations of the O3(ν2) and ground vibrational states as the system re-equilibrates. Relaxation rates are measured over a range of quencher concentrations to extract the rate coefficient of interest. The value of kO(ν2) was determined to be (2.2 ± 0.5) × 10(-12) cm(3) s(-1).