Ultraviolet and infrared absorption cross sections of gas phase HO 2 NO 2

Ultraviolet absorption cross sections for gas‐phase HO 2 NO 2 have been measured from 190 to 330 nm at 269 K and 20 torr total pressure. The HO 2 NO 2 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 HO 2 NO 2 in the stratosphere. High resolution infrared absorptivities for HO 2 NO 2 were also determined in the present study since these data are needed for possible quantitative evaluation of HO 2 NO 2 stratospheric concentrations. The infrared cross sections for the 802.7 and 1304.2 cm −1 Q‐branches of HO 2 NO 2 at 0.06 cm −1 resolution are 2.1 × 10 −18 and 1.8 × 10 −18 cm² molecule −1 , respectively.