Band Centers and Line Positions of Hot Bands of 13C16O2 and 16O13C18O in the 15 Micron Region

A high-resolution interferometer and high-temperature absorption cell have been used in a continuing measurement program of rotation-vibration spectra of the isotopes of carbon dioxide in different spectral regions. This paper covers results for the isotopes 13C16O2 and 16O13C18O with band centers in the spectral region 600 to 800 cm-1. Only a few experimental details will be given here; additional details may be found in the literature.1 The experimental components include an infrared source, a radiation chopper, a high-temperature single-pass gas-sample absorption cell, a Michelson interferometer with "cat’s eye" mirrors employing a step-and-integrate mirror motion, and two liquid-helium-cooled detectors. A carbon dioxide gas sample was contained in the 1.75 meter single-pass stainless-steel sample cell. The central one meter section of the cell was maintained at a temperature of 800K, with temperature gradients in the end segments of the cell, ending with the cell windows at room temperature. For this study a stepping mirror displacement of 75 cm was used, giving a resolution (FWHM) of 0.006 cm-1 with triangular apodization.