Quenching of the translationally hot and thermalized NH(c 1Π) radicals by HN 3

Abstract

The cross section for the quenching of NH(c 1Π, ν = 0) by HN 3 was measured by using a pulsed laser technique. A single rotational level of NH(c 1Π, ν = 0) was formed by exciting NH(a 1Δ, ν = 0) with a frequency doubled dye laser. NH(a 1Δ) was produced by photolyzing HN 3 with a XeCl excimer laser. The time profiles of the NH(c-a) fluorescence were measured at various pressures of HN 3. Experiments were performed both in the presence and in the absence of He buffer gas. In the absence of He, the NH radicals were found to be translationally hot; the average velocity was 3800±600 m s −1. The quenching cross sections for the translationally hot and thermalized NH(c) radicals by HN 3 were determined to be (28±5) × 10 −16 and (85±3) × 10 −16 cm 2, respectively. No rotational level dependence could be observed in the quenching of the hot NH(c) radicals.