15min:

V. MALATHY DEVI, D. CHRIS BENNER, The College of William and Mary, Williamsburg, VA 23187; M. A. H. SMITH, Science Directorate, NASA Langley Research Center, Hampton, VA 23681; A. W. MANTZ, Dept. of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320; K. SUNG AND L. R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.

Air-broadened line shape parameters were determined for the first time in the 2 0 bands of ¹³C¹⁶O near 4166.8 cm^-1 and ¹²C¹⁸O near 4159.0 cm^-1. Spectra were recorded at 0.005 cm^-1 resolution using a coolable absorption cell in the sample compartment of the Bruker IFS 125HR Fourier transform spectrometer at Jet Propulsion Laboratory. Gas temperatures and pressures ranged from 150 to 298 K and 20 to 700 Torr, respectively. Line parameters were determined by broad-band multispectrum least-squares fitting of the 4000-4360 cm^-1 region in 16 spectra simultaneously; each set included 4 isotope-enriched pure sample scans and 12 air+CO samples (¹³CO or C¹⁸O, as appropriate). The air-broadened parameters measured were Lorentz half-width coefficients, their temperature dependence exponents; pressure-induced shift coefficients, their temperature dependences; and off-diagonal relaxation matrix elements. Speed dependence parameters were included to minimize the fit residuals. For both isotopologues the individual line positions and intensities were constrained to their theoretical relationships in order to obtain the rovibrational (G, B, D, and H) and band intensity parameters, including Herman-Wallis coefficients. The results for ¹³C¹⁶O and ¹²C¹⁸O are compared with those for the ¹²C¹⁶O 2 0 band and discussed.