15min:

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

In a previous study we had reported N₂-broadening and pressure-induced shift coefficients for 34 rovibrational transitions in the ¹²C¹⁶O_{2 3} fundamental band near 4.3 µm. These parameters were determined from spectra recorded with the McMath-Pierce Fourier transform spectrometer (FTS) of the National Solar Observatory on Kitt Peak, Arizona. We now report similar measurements of N₂-broadening and shifts for transitions up to J''=56 in the ¹³C¹⁶O_{2 3} fundamental band, plus determinations of N₂-broadening coefficients in the ¹³C¹⁶O_{2 2}+ ₃- ₂ hot band and the ¹³C¹⁶O¹⁸O ₃ fundamental band. We also made new measurements of N₂-broadening and pressure-induced shift coefficients for rovibrational transitions up to J''=46 in the ¹²C¹⁶O_{2 3} fundamental band. These results were obtained from simultaneous analysis of five absorption spectra using a multispectrum nonlinear least-squares technique. A 4.08 cm sample cell at room temperature was used to record all of the spectra at 0.003 cm^-1 resolution with the McMath-Pierce FTS. This data set includes one low pressure (0.15 Torr) spectrum obtained with a 90% ¹³C-enriched CO₂ sample and four spectra of lean mixtures of the same ¹³CO₂ sample in N₂. Total pressures of the mixtures were between 101 Torr and 464 Torr. Because of the isotopic sample used, the ₃ fundamental bands of ¹²CO₂ and ¹³CO₂ appeared together in the same spectra, and we were able to obtain a consistent set of line parameters for both molecules. The present measurements represent the first experimental determination of N₂-broadening and pressure-induced shift coefficients in isotopic bands of CO₂ in the 4.3 µm region. The results obtained for the various bands will be compared with each other, with the values in the HITRAN database, and with available values reported in the literature.