Ultraviolet and infrared absorption cross sections of gas phase HO2NO2

Ultraviolet absorption cross sections for gas‐phase HO2NO2 have been measured from 190 to 330 nm at 269 K and 20 torr total pressure. The HO2NO2 cross sections vary smoothly from 1.6 × 10−17 cm² molecule−1 at 190 nm to ˜2 × 10−20 cm² molecule−1 at 330 nm, and thus photolysis may be the major loss process for HO2NO2 in the stratosphere. High resolution infrared absorptivities for HO2NO2 were also determined in the present study since these data are needed for possible quantitative evaluation of HO2NO2 stratospheric concentrations. The infrared cross sections for the 802.7 and 1304.2 cm−1 Q‐branches of HO2NO2 at 0.06 cm−1 resolution are 2.1 × 10−18 and 1.8 × 10−18 cm² molecule−1, respectively.