Quantitative Spectroscopic Studies of the HO2 Radical: Band Strength Measurements for the ν1 and ν2 Vibrational Bands

Article abstract of DOI:10.1021/j100340a010

Infrared line intensities in the three fundamental vibrational bands of the HO2 radical have been measured by using a tunable diode laser coupled with a low-pressure discharge flow system.Relative intensity measurement comparing line in the ν₂ and ν₃ bands and in the ν₁ and ν₂ bands are combined with calculated line intensity-band strength ratios to obtain the band strength ratios S_v(ν₂)/S_v(ν₃) = 1.7 +/- 0.2 and S_v(ν₁)/S_v(ν₂) = 0.34 +/- 0.07.These ratios may be combined with our previous measurement of the absolute band strength for the ν₃ band, S_v(ν₃) = 35 +/- 9 cm^-2 (STP atm)^-1, to obtain S_v(ν₂) = 58 +/- 16 cm^-2 (STP atm)^-1 and S_v(ν₁) = 20 +/- 6 cm^-2 (STP atm)^-1.The strongest features for monitoring HO2 concentrations by infrared absorption in laboratory or field experiments are the nearly coincident line pairs in the ν₂ band at 1371.927 or 1411.180 cm^-1, both of which have combined line intensities of (1.2 +/- 0.3) x 1E-20 cm² molecule^-1 at 296 K.