A study of the UV-visible absorption spectrum of molecular chlorine

Abstract

The UV-visible absorption spectrum of molecular chlorine at 298 K was investigated in the wavelength range 200-550 nm with a spectral resolution of 0.2 nm. Except for minor discrepancies, the absorption cross-sections are in agreement with those found in the literature. In the region 250≤λ≤-550 nm, the Cl2 spectrum can be adequately described by a semi-empirical function of the wavelength A (in vacuum) and temperature T {A figure is presented} where tanh=tanh(hcx559.751 cm-1/2kT). The absorption of solar radiation by the weak continuum around λmax=406.5 nm contributes 9% or more of the photodissociation of molecular chlorine in the atmosphere, but the banded Cl2 features (λ ≥ 479 nm) are of negligible atmospheric significance. © 1993.