Magnetic resonance studies of triatomic free radicals in the gas phase

An investigation of the gas phase EPR spectrum of the HO2 radical at a frequency of 9 GHz is reported. The data are combined with the measurements of the far infrared LMR spectrum and the zerofield microwave spectrum that have been reported in the literature, and fitted to a molecular Hamiltonian to determine an extensive set of ground state parameters which are subsequently discussed. The detection of lines in both the gas phase EPR spectrum at 9 GHz and the far infrared LMR spectrum of the D02 radical is reported. The data are fitted to an appropriate Hamiltonian and several ground state parameters are determined. The presence of transitions involving two different components of the electricdipole moment in the EPR spectrum, allows the ratio of the magnitudes of these components to be calculated. A combination of the parameters for HOt with chose for D02 permits the ro molecular geometry to be calculated more reliably than before. The detection of lines in the infrared LMR spectrum of NCO is also reported. The spectrum arises from absorption by the highest frequency fundamental vibration, and provides the first determination of this frequency to be obtained from a gas phase study.