Part of the far-infrared laser magnetic resonance spectrum of the HF + free radical

Abstract

Transitions between the spin-rotational levels of the HF + radical in the v=0 level of the X 2Π ground state have been observed by the technique of laser magnetic resonance at far-infrared wavelengths. Because of the large spin–orbit coupling in this 2Π state, the detection of the fine-structure transitions required the use of very short-wavelength laser lines (down to 40 μm). These observations have provided accurate information on the 19F hyperfine splittings in rotational levels of the upper 2 Π 1/2 spin component for the first time which has enabled the complete determination of the hyperfine structure for this molecule. An effective Hamiltonian was used to model the experimental measurements; this provided considerably more accurate values for the various molecular parameters than previously available. Using these parameters, predictions of the transition frequencies between the low-lying spin-rotational levels of the radical at zero magnetic field have been made.