Air-broadening parameters in the ν3 band of 14N16O2 using a multispectrum fitting technique

Air-broadened linewidths, pressure-induced shift coefficients and their temperature dependences were retrieved for over 1000 transitions in the ν 3 band of 14 N 16 O 2 at 6 μm. In addition, precise line center positions and relative intensities were also determined. The results were obtained by fitting simultaneously 27 spectra recorded at high resolution (0.002–0.006 cm −1 ) with two Fourier transform spectrometers and gas sample temperatures ranging from 206 to 298 K. It was necessary to modify the multispectrum fitting software to accommodate constraints on the retrieved parameters of closely spaced spin–split doublets in order to successfully determine their broadening and shift parameters. The variations of the widths, shifts and their temperature dependences with the quantum numbers were investigated. Subsets of the observed linewidths were reproduced to within 3% using an empirical smoothing function.