Magnetic rotation molecular spectroscopy using an oscillating field

The high resolution magnetic rotation spectrum of a diatomic molecule is co nsidered. A procedure is described for calculation of the magnetic rotation signal in both first and second harmonic for an oscillating magnetic field in the low-field limit. The procedure is simpler than other methods availa ble in the literature, and a more complete account is taken of the various possible contributions to the signal. Perturbations between electronic stat es that make it possible to observe magnetic rotation signals for high-J tr ansitions are discussed, along with the associated evolution of line shape that complicates frequency measurements from magnetic rotation spectra. Exa mples are given from a recent magnetic rotation study of the A (3)Pi (1u)-X (1)Sigma (+)(g) system of Br-79(2). (C) 2000 American Institute of Physics . [S0021-9606(00)30843-1].