Absorption cross-sections and pressure broadening of rotational lines in the 3 ν3 band of N 2O determined by diode laser cavity ring-down spectroscopy

Abstract

Diode laser cavity ring-down spectroscopy (CRDS) has been used to measure rotational line intensities and air pressure broadening coefficients for the 3 ν 3 (N–N stretching) vibrational overtone band of N 2O. The line intensity measurements are in quantitative agreement with previously reported Fourier transform spectroscopy results [J. Mol. Spectrosc. 197 (1999) 158]. The air pressure broadening coefficients increase from 0.086 ± 0.015 cm −1 atm −1 for the P(34) line to 0.139 ± 0.010 cm −1 atm −1 for the P(3) line, and are greater than values reported for other ro-vibrational bands of N 2O observed at lower frequencies. The effects of pressure broadening on line-centre absorption cross-sections, and thus for the sensitivity of CRDS detection of N 2O using narrow bandwidth near-IR lasers are quantified.