The Far-Infrared Laser Magnetic Resonance Spectrum of CH2F

Abstract Far-infrared laser magnetic resonance (FIR-LMR) spectra due to the CH 2 F radical have been recorded on seven laser lines at wavelengths between 301 and 568 μm. Observed resonances were assigned to fine and hyperfine components of pure rotational transitions of CH 2 F in the ground vibrational state and the first excited state of the ν 4 out-of-plane bending mode. All assigned transitions obey a -dipole selection rules. The data were combined with previously reported microwave results (Y. Endo, C. Yamada, S. Saito, and E. Hirota, J. Chem. Phys. 79, 1605 (1983)) and subjected to a least-squares fit to determine the parameters of the effective Hamiltonian describing the v 4 = 0 and 1 vibrational levels of the CH 2 F radical.