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 Ka =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), εaa=−26 039(38), εbb=−381.7(29), εcc =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: re (O–H)=0.9707±0.0020 Å, re(O–O)=1.330 54 ±0.000 85 Å, and θe (HOO)=104.29±0.31 Å.