Detection of LiH and NaH molecular beams by laser fluorescence and measurement of radiative lifetimes of the A 1Σ+ state

Abstract

We report here detection of supersonic molecular beams of LiH and NaH using the tunable laser fluorescence technique. From measurement of the relative intensities of individual rotational lines in the excitation spectrum, beam rotational temperatures T_rot=600±100 °K for LiH and T_rot= 230±50 °K for NaH have been obtained. Direct measurement of the fluorescence decay of excited A ¹Σ⁺ state molecules after pulsed laser excitation has allowed determination of the radiative lifetimes of several (v′,J′) levels. We find τ (v′=2,J′=3) =29.4±1.3, τ (v′=5,J′=3) =30.5±1.3, and τ (v′=7,J′=12) =36.9±1.9 nsec for ⁷LiH and τ (v′=8,J′=3) =22.7±1.6 nsec for ²³NaH, where the quoted uncertainties represent three standard deviations. These values agree to within the ∼10% quoted experimental uncertainties with theoretical lifetimes calculated using ab initio electronic transition moments of Docken and Hinze (LiH) and Sachs, Hinze, and Sabelli (NaH).