A shock tube study of vibrational relaxation of O2 in argon by small amounts of H2 (860–1290 K), D2 (890–1070 K), and He (1000–1500 K)

Abstract

Vibrational relaxation times of O2 in a mixture of 2% O2 in Ar were measured behind reflected shock waves at temperatures of 1000–1600 K and total pressures of 2–3 atm. The effects of small amounts (0.05%–0.3%) of H2 (860–1290 K), D2 (890–1070 K), and He (1000–1500 K) on the relaxation times were measured, the effects being consistent with the linear mixture rule. At the D Ly-α wavelength (121.6 nm), new values of the absorption cross sections for vibrationally excited O2 are σ1 (for v=1)=(3.4±1)×10−19 cm2, and σ2 (for v=2)=(5±2)×10−18 cm2.