Measurement of the Lifetime of theAΠ1State of CO by Level-Crossing Spectroscopy

The lifetime of the $v=2\mathrm{}$ level of the $A{}_{}{}^1{}_{}{}^{}\Pi$ state of CO has been measured by molecular level-crossing spectroscopy. Unlike previous experiments with molecules in which the Hanle effect has been analyzed for individual rotational states, the present results are obtained from analysis of the composite level-crossing signal from all of the rotational states which are excited by the entire $A\to X(2, 0)$ resonance band. Our experimental result is $\tau \mathrm{}(v=2\mathrm{})=9.0\mathrm{}\pm 1.0$ nsec in good agreement with Hesser's value of 10.5 ± 1.0 nsec obtained from phase-shift experiments.