Infrared laser magnetic resonance of gaseous free radicals

Vibration-rotation transitions of the open shell molecules NH2, HCO and a third, unidentified species, have been studied using an infrared carbon monoxide laser magnetic resonance spectrometer. Details of the spectrometer; the theory of vibration-rotation laser action in CO and the methods of selecting oscillating transitions are presented. The effective Hamiltonian describing an asymmetric top free radical in the presence of an external magnetic field is given and subsequently used in the analysis of the spectra of NH2 and HCO.Transitions in NH2 invlove the bending fundamental and have been assigned to members of the R-branch. Measurements of the resonances have been used to determine the vibrational interval (1497 3215(12)cm 1) and the major molecular parameters for NH2 in the (0, 1, 0) level. A similar analysis is presented for transitions arising from theCO stretching fundamental in the HCO radical. The transitions have been assigned to members of the P, Q and R-branches and measurements of the resonances have been used to determine the vibrational interval (1868.1714(5)cm 1) and the major molecular parameters for HCO in the (0, 1, 0) level. The detection of transitions around 1859cm 1, arising from an unidentified molecule is described, followed by a discussion of the possible identity of the absorbing species.