High-Resolution Laser Excitation Spectroscopy of theB̃2Σ+–X̃2Σ+System of Jet-Cooled SrOD

Abstract

The high-resolution laser excitation spectrum of the 001–000 and 000–000 bands of theB2Σ+–X2Σ+transition of SrOD was recorded. The SrOD molecules were made by pulsed laser ablation of Sr metal followed by reaction with D2O. Sub-Doppler resolution and rotational cooling were achieved by expansion into vacuum and excitation with a cw dye laser perpendicular to the molecular beam. A molecular linewidth of 200 MHz and the lack of spectral congestion allowed aQbranch to be detected. Spin–orbit mixing between theA2Π andB2Σ+states caused the unusual appearance of a moderate intensityQbranch in a nominally parallel2Σ+–2Σ+transition. From the relative intensities of the rotational lines, the ratio of the perpendicular to the parallel transition dipole moment was found to be 0.2 to 0.3.