Rotational relaxation rate constants for CO2

Abstract

Rotational relaxation rate constants, k_rot, have been measured for the CO₂ 00°1 level in three kinds of amplifiers: one using CO₂ alone and two others using mixtures of CO₂–He and CO₂–N₂. The experiment consists of perturbing the CO₂ 00°1 level with a ∼2‐nsec saturating pulse at P(20) in the 10.4‐μ band and monitoring the subsequent repopulation of the J = 19 rotational state with a probe beam set at P(20) in the 9.4‐μ band. The determined rate constants are kCO₂–CO₂ = 1.3±0.2, kCO₂–He = 0.6±0.1, and kCO₂–N₂ = 1.2±0.2, all in units of 10⁷ sec⁻¹ Torr⁻¹.