Electric quadrupole and dipole transitions of the first overtone band of HD by CRDS between 1.45 and 1.33 μm

Abstract

The first overtone band of HD has been recorded by CW-Cavity Ring Down Spectroscopy between 6900 and 7900 cm −1. The noise equivalent absorption of the spectra was on the order of α min ≈ 5 × 10 −11 cm −1. Eleven dipole electric transitions – P(1)– P(2) and R(0)– R(8) – and nine quadrupole electric transitions – Q(1)– Q(4) and S(0)– S(4) – were accurately measured. The uncertainty on the line positions and the line strengths is on the order of 0.001 cm −1 and 2%, respectively. The minimum intensity reported is 1.04 × 10 −30 cm/molecule for the R(8) line which is the most rotationally excited absorption line of hydrogen reported so far. The dipole and quadrupole transition moments were derived from the measured line strengths. The agreement with the most recent theoretical calculations is found to be within the experimental uncertainty for both line positions and line intensities.