Indirect Method for Measuring Spectral Linewidth, with Application to N_2O*

Abstract

When spectral band models are applied to small-frequency intervals within a band, the parameter γ⁰/d may be derived for these intervals. For the case of an Elsasser band the quantity d is equal to the distance between adjacent lines. Since line positions are known for many molecular bands it is possible to derive d and hence γ⁰, the line width in each interval. It follows that by this method γ⁰ is derived from low-resolution transmittance measurements. The method is shown to be accurate within ±20% for the fundamental vibration band of CO and is then applied to the 4.5-μ band of N₂O. In part of this band the value of γ⁰ is found to be 0.08 cm⁻¹atm⁻¹ at 300°K for nitrogen broadened N₂O.