Rotational spectroscopy of DO2 by FIR LMR and millimeter-wave absorption

Abstract

We report the measurement of approximately 50 rotational transitions in the DO2 radical between 230 and 2530 GHz by high-resolution millimeter-wave and far-infrared laser magnetic resonance spectroscopy. The radical was generated in the gas phase by the reaction of chlorine atoms and oxygen or discharged oxygen with deuterated methanol. The data were analyzed in conjunction with previously published high-resolution spectra of the molecule in the ground vibronic state in order to extract the best set of parameters in the effective Hamiltonian describing the model. The fine structure (spin-rotation) parameters derived in the present work were used together with those for HO2 [A. Charo and F.C. De Lucia, J. Mol. Spectrosc. 94, 426-436 (1982)] in order to determine all of the symmetry-allowed spin-rotation tensor components for the hydroperoxyl radical. The results cannot be interpreted in terms of contamination of the ground state wavefunction by the lowest lying A~2A' state alone and information from quantum chemical calculations of spin-orbit matrix elements between the ground and higher excited states or additional experimental data involving high excited electronic states are necessary before a complete rationalization of the results is possible.