The EPR and LMR spectra of the DO2 radical: Determination of ground-state parameters

The detection of lines in both the gas phase EPR spectrum at 9 GHz and the far-infrared LMR spectrum of the DO₂ radical is reported. The measurements are fitted with an appropriate Hamiltonian and several parameters for the molecule in the $\text{X}\text{?}{}^2\text{A″}$ state are determined. The majority of the transitions in the EPR spectrum are K-type doubling transitions and involve the a-component of the electric dipole moment. However the observation of one b-type transition (5₀₅-4₁₄) permits the determination of the off-diagonal component of the spin-rotation tensor, ?_ab, and an estimate of the relative magnitudes of the a- and b-components of the dipole moment. A combination of the parameters for HO₂ with those for DO₂ leads to a better understanding of the properties of the molecule. In particular, the r₀ molecular geometry has been determined more reliably than previously to be $\text{r}{}_0\text{(OH) = 0.9774}\text{A}\text{?}$, $\text{r}{}_0\text{(OO) = 1.3339}\text{A}\text{?}$, ∠HOO = 104.15°.