IR absorption in crossed jets: relative rotational energy transfer efficiencies for CO(J=0,1) with He, N2, and Ar

Abstract

A seeded free jet of CO was crossed perpendicularly with a second free jet of collider molecules. Direct absorption of a tunable IR diode laser beam was used to measure relative cross sections for translational to rotational energy transfer (RET) in low rotational states of CO. Multiquantum rotational transitions populating a broad range of final J states were demonstrated to be important. The relative, net depletion rates of CO(J=O) and CO(J=1) were measured and used to estimate the total RET cross sections. Subject to inaccuracies of ±10% in the measured flow rates, the relative, total, RET cross sections σ He :σ N2 :σ Ar , were found to be 1:1.7:2.0 (±20%) for CO(J=O)