PNNL

Abstract

Air-broadened line widths, pressure-induced shift coefficients and their temperature dependences were retrieved for over 1000 transitions in the v3 band of 14N16O2 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 cm-1 to 0.006 cm-1) with two Fourier transform spectrometers and gas sample temperatures ranging from 206 K 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 on the quantum numbers were investigated. Subsets of the observed line widths were reproduced to within 3% using an exponential smoothing function.