Nitrogen- and water-broadening coefficient measurements in the A˜2A′←X˜2A″ 000-000 band of HO2 using high-resolution diode laser two-tone frequency modulation spectroscopy

The line shape profiles of the A˜2A′←X˜2A″ 000-000 band of hydroperoxy radical (HO2) have been measured in the presence of nitrogen and water using laser photolysis/cw near infrared two-tone frequency modulation spectroscopy. On the basis of the theory described by Avetisov and Kauranen [Appl. Opt. 35 (1996) 4705], the absorption line shapes were well represented by the Voigt profile. The nitrogen- and water-broadening coefficients for the 7020.766 cm−1 161, 16 ← 160, 16F1 line of HO2 were estimated to be 0.101 ± 0.013 and 0.216 ± 0.133 cm−1 atm−1, respectively. The large value of water-broadening coefficient suggests the long range interaction between HO2 with water.