Ultraviolet absorption spectrum of HOCl

Abstract

The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 ± 0.3) × 10−19 cm2 ( 2 σ error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988]). An HOCl ν2 infrared band intensity of 230 ± 35 cm−2 atm−1 was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.