Kinetics of OH Radicals Determined by Their Absorption Spectrum IV. Pressure Broadening and the Line Spectrum as Background

Abstract

For the measurement of the concentration of OH radicals the intensity of the absorption spectrum is measured more easily with an emission line background than with a continuous background, provided that the pressure broadening is known. The total broadening of the OH absorption lines at 1473° K and 1 atmos. (⅔O₂+⅓H₂O) is observed to be 0.58 cm^—1; 36 percent of this value is Doppler broadening, the rest is pressure broadening. With this figure, recent intensity measurements of the OH bands by Avramenko and Kondratjew are reinterpreted. The resulting f values of approximately 3×10^—4 are in reasonable agreement with our previous measurements. The conditions are discussed under which the simple method using the line spectrum as a background is applicable.