Predissociation linewidths of the (1,0)–(12,0) Schumann–Runge absorption bands of O2 in the wavelength region 179–202 nm

Abstract

A nonlinear least-squares method of retrieving predissociation linewidths from the experimental absolute absorption cross sections of Yoshino et al. [Planet. Space Sci. 31, 339 (1983)] has been applied to the (1,0)–(12,0) Schumann–Runge bands of oxygen. Predissociation linewidths deduced for the Schumann–Runge bands are larger than the theoretical predictions of Julienne [J. Mol. Spectrosc. 63, 60 (1976)] and the latest measurements of Lewis et al. [J. Quant. Spectrosc. Radiat. Transfer 36, 187 (1986)]. The larger linewidths found will have an impact on calculations of solar flux penetration into the Earth’s atmosphere and of the photodissociation rates of trace species in the upper atmosphere. Systematic variation of predissociation linewidths with rotational quantum number is observed in the bands (v′,0) with v′=6, 8, 9, 11, and 12.