The ν1 band of the DO2 radical by difference frequency laser and diode laser spectroscopy: The equilibrium structure of the hydroperoxyl radical

Abstract

The ν₁ band of the DO₂ radical was observed by difference frequency laser and diode laser spectroscopy with Zeeman modulation. The radical was produced by a 60 Hz discharge in a mixture of CH₃OD or CD₃OD and O₂ flowing through a multiple reflection absorption cell. The observed lines, 181 in total, of six subbands with K_a =2←3, 1←2, 0←1, 1←0, 2←1, and 3←2 were included in a least‐squares analysis to determine molecular parameters for the upper state: A=326 929.3(92), B=31 683.68(36), C=28 779.96(46), ε_aa=−26 039(38), ε_bb=−381.7(29), ε_cc =4.3(22), in MHz, and the band origin ν₀=2 549.224 65(36) cm⁻¹, where the values in parentheses denote one standard error in units of the last quoted decimal place. By combining this data with that for the ν₂ and ν₃ bands of DO₂ by Uehara et al. and that for HO₂ already available in the literature, the equilibrium structure of the hydroperoxyl radical was calculated with estimated uncertainties: r_e (O–H)=0.9707±0.0020 Å, r_e(O–O)=1.330 54 ±0.000 85 Å, and θ_e (HOO)=104.29±0.31 Å.