Lifetimes of the CO metastable a 3Π(v⩽3,Ω,J) levels

Abstract

We reanalyze the theoretical lifetimes of the metastable ${\mathrm{a }}^3\text{Π(v=0,Ω,J)}$ levels as well as the spontaneous ${\mathrm{a }}^3\text{Π(v=0)}$ decay rates into the ${\mathrm{X }}^1{\Sigma }^{+}\mathrm{(v)}$ ground state levels, clearly favoring the measurements of Jongma et al. [J. Chem. Phys. 107, 7034 (1997)] as compared to the theoretical results of James [J. Chem. Phys. 55, 4118 (1971)]. Theoretical lifetimes of the vibrationally higher lying metastable levels ${\mathrm{a }}^3\text{Π(v=1–3,Ω,J)}$ are listed for the first time. The lifetimes of the two Λ components are shown to be different. A new technique for measuring the lifetime of individual rovibrational metastable molecular levels is applied to the CO rovibrational level ${\mathrm{a }}^3\text{Π(v=3,Ω=1,J=2).}$ Our result $\text{τ=3.04±0.38\hspace{0.05em}}\mathrm{ms}$ is in good agreement with the theoretical lifetime of 2.97 ms. The metastable population is deduced to be $N_{\mathrm{meta}}{\text{=(2.3±1.2)⋅10}}^6 \mathrm{molecules/shot}.$ Finally, our ms lifetime measurement technique is compared with that developed by Jongma et al. [J. Chem. Phys. 107, 7034 (1997)].