PRESSURE BROADENING AND PRESSURE SHIFT COEFFICIENTS IN THE 2 ν02 AND ν1 BANDS OF 16O 13C 18O

Abstract

In this study we report the first measurements of the pressure broadening and the pressure-induced line shift coefficients due to air and nitrogen for 93 individual rovibrational lines, P(46) to R(46) and P(50) to R(45), respectively, belonging to the 2 ν 0 2 and ν 1 bands of 16O 13C 18O. The results were obtained by analyzing ten long path, high-resolution laboratory absorption spectra using a multispectrum nonlinear least-squares technique. Broadening due to nitrogen was about 4% larger than by air. Similar to broadening coefficients, the pressure-shift coefficients were found to be transition dependent, but different for the P- and R-branch lines with the same rotational quantum number, J. Except for a few R-branch lines, the measured shift coefficients were negative. The shift coefficients varied from +4×10 -3 cm -1 atm -1 at 296 K to −5.6×10 -3 cm -1 atm -1 at 296 K. Comparisons of the broadening and shift coefficients between the two bands, between the P and R branches, and between the two broadening gases are reported. No significant difference between shift coefficients of the two bands or the two broadening gases was observed. The results obtained were compared with those reported in the literature for the more abundant 12C 16O 2 species.