Laboratory investigation of the absorption and emission of infrared radiation

Abstract

Extensive measurements of the absorption by H 2O and CO 2 have been made in the region from 0·6 to 5·5 microm. Two different multiple-pass absorption cells provided path lengths from 2 to 933 m, and sample pressures were varied from a few μHg to 15 atm. Approximately thirty new CO 2 bands were observed and identified, and the strengths of the important bands determined. The H 2O data provide enough information for the determination of the strengths and widths of several hundred of the more important lines. The wings of CO 2 absorption lines were found to be sub-Lorentzian, with the shapes depending on temperature, broadening gas, and wavelength in ways which cannot be explained by present theories. The absorption by H 2O and CO 2 samples at temperatures up to 1800°K has been studied from 1 to 5 microm. The transmission of radiation from hot CO 2 through cold CO 2 and from hot H 2O through cold H 2O has been investigated to determine the effect of the coincidence of emission lines with absorption lines.