Broadband v3 sub-Doppler spectrum of HCN: application of a color center laser optothermal molecular beam spectrometer

A broadband v3 sub-Doppler spectrum of HCN has been recorded in the range 3340–3280 cm−1 using a single frequency continuously scanable computer-controlled color center laser optothermal molecular beam spectrometer. Absolute frequencies for rovibrational transitions R(9) through P(9) have been determined to an accuracy ≤ 20 MHz or 2 parts in 107. An unconstrained five-parameter fit to this datum results in molecular constants: B″ = 1.47822146(182), D″ = 2.881(23) × 10−6, B′ = 1.46779974(154), D′ = 2.863(18) × 10−6, and v0 = 3311.47758(2) cm−1, respectively.