Near infrared spectroscopy of carbon dioxide. II: 16O 13C 16O and 16O 13C 18O line positions

Abstract

High-resolution near-infrared (4000–8500 cm −1) spectra of 13C-enriched carbon dioxide have been recorded using the McMath-Pierce Fourier transform spectrometer at the Kitt Peak National Solar Observatory. We observed over 1000 line positions for the 16O 13C 16O isotopologue, the majority of which have previously been observed only in spectra of the Venusian atmosphere [J. Mol. Spectrosc. 67 (1977) 304]. These have been analyzed to determine spectroscopic constants for 28 different vibrational states. The analysis yielded RMS fitting residuals <1.5 × 10 −4 cm −1 for the strongest bands and RMS residuals <5 × 10 −4 cm −1 for most other fitted bands. A 5% 18O-enrichment in the sample enabled us to observe 410 line positions from 5 near-infrared vibrational bands of the 16O 13C 18O isotopologue. Analysis of the 16O 13C 18O bands yielded RMS fitting residuals <2 × 10 −4 cm −1. Additionally, the first fits for the 16O 13C 18O 11101 ← 01101 and 11102 ← 01101 hot bands yielded RMS residuals of 2.3 × 10 −4 and 2.2 × 10 −4 cm −1, respectively. Critical reevaluations of the spectroscopic constants for the low lying vibrational states for both isotopologues have been performed as part of the analysis.