$CO_{2}$ BANDS IN THE $3350 - 3700 cm^{-1}$ SPECTRAL REGION: RO-VIBRATIONAL CONSTANTS AND ABSOLUTE INTENSITIES.

Abstract

Spectroscopic constants and absolute intensities from more than 2150 transitions belonging to 52 bands of 7 isotopic species of carbon dioxide have been determined using a multispectrum nonlinear least-squares fitting $technique.^{1}$ The spectral data ($0.01 cm^{-1}$ resolution) were obtained at room temperature and low pressure (<10 Torr) using the McMath-Pierce Fourier transform spectrometer of the National Solar Observatory on Kitt Peak, Arizona. A natural sample of carbon dioxide with absorption path lengths between 24 and 385m were used in recording the spectra. The first measurements have been made of the theoretically $predicted^{2} 2\nu_{2}{^{2}} + \nu_{3}$ "forbidden" band of ${^{12}}CO_{2}$. Two bands which have not been predicted so far, one belonging to ${^{13}}CO_{2}$ and the other to ${^{13}}C{^{16}}O{^{18}}O$, have been identified. The measured line intensities obtained for each band have been analyzed to determine the vibrational band intensity and F-factor coefficients. The results are compared to the values used to calculate the intensities in the 1992 HITRAN $database^{2}$. Simulations illustrating the differences in spectra predicted with the new lines and the HITRAN 1992 $lines^{2}$ are presented along with comparisons to stratospheric and laboratory spectra.