The Nitric Oxide Fundamental Band: Frequency and Shape Parameters for Rovibrational Lines

Solar McMath FTS spectra, recorded with a full instrumental width of about 0.0064 cm −1, were obtained of the fundamental vibration-rotation band (υ = 1 ← 0) of 14N 16O. These spectra have been used to determine N 2-induced-broadening and N 2-induced-shift coefficients as well as line intensities and positions. Measurements were made from 1780 to 1952 cm −1, up to | m| ≍ 22.5, for the P and R branches of the 2Π 1/2 and 2Π 3/2 subbands and a few transitions of the Q branch. The rotationless transition moments of the two sub-bands were found to be within 1 2 % of each other. The first-order Herman-Wallis intensity factor, C, measured for the first time, is in excellent agreement with theoretical predictions. The band intensity is 114.9 ± 3.4 cm −2 atm −1 at 296 K. The v = 1 ← 0 N 2-broadened widths and N 2-induced pressure shifts are, respectively, 3% different and a factor of 2 smaller than those measured by Pine et al. [ J. Mol. Spectrosc. 114, 132-147 ( 1985 ) ] for the v = 2 ← 0 band. The broadening coefficients are, where comparisons can be made, a few to about twenty percent smaller and the intensities about four percent larger than results reported by Ballard et al. [ J. Mol. Spectrosc. 127, 70-82 (1988)]. Line positions are retrieved and calibrated to an accuracy of ±5 × 10 −5 cm −1 using the 1-0 band of CO. Comparisons of calculated positions based on the constants of Hinz et al. [ J. Mol. Spectrosc. 119, 120-125 ( 1986)] reveal very good agreement for the 2Π 3/2 subband and a systematic divergence for the 2Π 1/2 positions. The effects of hyperfine splittings are also detected for low m transitions.