15min:

M. A. H. SMITH, C. P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199; A. W. MANTZ, Department of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320; D. CHRIS BENNER AND V. MALATHY DEVI, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795.

Self- and hydrogen-broadening and pressure-shift coefficients for the first overtone band transitions of ¹²C¹⁶O at room temperature have been determined through analysis of nine high-resolution (0.005 cm^-1) absorption spectra. These spectra were recorded using the 1-m Fourier transform spectrometer (FTS) at the McMath-Pierce facility of the National Solar Observatory on Kitt Peak, Arizona. Eight of the nine spectra (including the three H₂-broadened spectra) were recorded using a high-purity CO sample having natural isotopic composition, and a single self-broadened spectrum was obtained using a CO sample having 99.999 atom % ¹²C. A Pyrex cell with 10 cm path length was used to record all of the spectra. Self-broadened sample pressures ranged from about 3 to 507 Torr, and the H₂-broadened spectra had total pressures of 155 to 475 Torr. Because of the short path length of the cell, the volume mixing ratios of CO in H₂ were relatively high, approximately 18% to 22%, to achieve measurable absorption in the 2-0 band. These mixing ratios necessitated the simultaneous determination of the CO self-broadening and self-shift coefficients along with the H₂-broadening and H₂-induced shift coefficients. We have determined these coefficients at room temperature, along with line positions and intensities, for the P(26) through R(22) ¹²C¹⁶O 2-0 transitions by fitting the entire spectral interval from 4130 to 4360 cm^-1 in all nine spectra simultaneously. Our multispectrum nonlinear least-squares procedure was used to retrieve these spectral line parameters. The results will be compared to previous published values where possible.