Laser Excitation Spectra and Lifetime Measurements of the CO d(3Δi)State

CO in a supersonic pulsed beam is excited to the d3Δi state by VUV photons generated in a nonlinear four-wave mixing scheme. An excitation spectrum of the CO d3Δi (ν′ = 20, J′ = 1–3) is obtained at a resolution of 0.8 cm−1 for the first time. The radiative lifetimes of the rotational states are measured as 1.70 ± 0.08 μs, which are similar to but shorter than the lifetimes associated with lower vibrational levels.