Abstract

Atmospheric measurements of nitric acid are relevant both in the troposphere, where it is a precursor of inorganic free radicals as well as of nitrates and aerosols¹, and in the stratosphere², where it is a principal repository of odd nitrogen^3,4. Single frequency laser detection offers the possibility of distinguishing nitric acid from other atmospheric species if the effective extinction coefficient for a given laser line is known; such information on more than one line heightens the discrimination. Recently, the constants of the Hamiltonian for this band have been published⁵, so that the transition frequencies and relative line strengths may be calculated. This information has been combined with transmittance data at four different CO laser frequencies which are coincident with the v₂ band of nitric acid such that the extinction coefficient is determined for each laser frequency. In addition, the b-component of the transition moment for the band is found at each CO laser line used; these values are consistent among themselves and overlap the earlier determination of Goldman et al. ⁶ within the quoted uncertainties.

© 1980 Optical Society of America