The temperature dependence of the ClONO2 absorption spectrum has been
measured between 220 and 298 K and between 195 and 430 nm using a diod
e array spectrometer. The absorption cross sections were determined us
ing both: (1) absolute pressure measurements at 296 K and (2) measurem
ents at various temperatures relative to 296 K using a dual absorption
cell arrangement. The temperature dependence of the ClONO2 absorption
spectrum shows very broad structure. The amplitude of the temperature
dependence relative to that at 296 K is weak at short wavelengths, <
2 % at 215 nm and 220 K, but significant at the wavelengths important
in the stratosphere, approximately 30 % at 325 nm and 220 K. Our ClONO
2 absorption cross section data are in good general agreement with the
previous measurements of Molina and Molina [1979].