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.

Calculated vibrational structure of the first band of the photoelectron spectrum of HO−2 and the electron affinity of HO2

“…This potential is not perfect, but should be good enough for our purposes. The correspondin~ equilibrium structure is r~ = 0.9716~,, R e = 1.3304 A and c~ = 104.307 °, in very close agreement with values derived from high-resolution spectroscopy [22,23]. Compared to our CCSD(T) calculations for HO2-, there is a substantial decrease of 0.192 A in the OO equilibrium bond length.…”

“…Using the PEF of Bunker et al [20], the wavenumbers of the fundamentals for DO2 are calculated to be 1025.4 (1020.16), 1117.4 (1121.47) and 2550.3 (2549.22) cm -~, with experimental values [22,24,25] given in parentheses. The vibrational mode with lowest wavenumber is mostly DOO bending in character and will therefore be designated vz in order to maintain the analogy with HOe.…”

Fugacity coefficients for free radicals in dense fluids: HO2 in supercritical water

“…Lubic et al, 1984Lubic et al, 1984Lubic et al, 1984Uehara et al, 1985Uehara et al, 1985Uehara et al, 1985 Weiner et al, 1986Weiner et al. 1986Weiner et al, 1986Weiner et al.…”

“…Lubic et al (1984) reported the equilibrium geometry of the hydroperolryl radical in the ground state (,A'), and Table 1 displays the bond lengths and bond angle.…”

A modified potential for HO2 with spectroscopic accuracy

“…18 The potential was forced to reproduce the experimental equilibrium geometry, 19 dissociation energy, 15 and quadratic force constants 4,20 of the hydroperoxyl radical. Again the vibrational information was included using the harmonic force field.…”