Determination of collisional quenching rate coefficient of by H2O

Abstract

The measurement of the effective lifetime of in mixtures of nitrogen and small amounts of H2O (10.2 and 103 ppm) was carried out while observing the transient ionization current after turning off the ultraviolet (UV) light illuminating the cathode in a non-self-sustained Townsend discharge region. The transient current was formed by the emitted current sustained by the γm action of metastable excited molecules , which were produced by the impact of electrons with nitrogen molecules in the gap, and returned to the cathode by diffusion. Then, the collisional quenching rate coefficient of by H2O, the diffusion coefficient of , and the reflection coefficient of at the cathode surface were determined from the observed effective lifetime of by an analytical procedure based on solving the diffusion equation. The obtained collisional quenching rate coefficient of by H2O was (5.7 ± 0.6) × 10−13 cm3 s−1.