Magnetic-field-induced transition in the oxygen A band

We investigated the magnetic-field-induced transition of the oxygen molecule in the region of the forbidden electronic band b(1) Sigma(g)(+) (upsilon' = 0) - X-3 Sigma(g)(-) (upsilon = 0). To detect the induced transition we used the resonant Voigt effect (magneto-optic effect in a transverse magnetic field). An elliptically polarized beam of light from a laser was frequency-tuned to the rotational lines of the band, which could be designated as the O-P(K, J) and S-R(K, J)-branch lines and the (P)Q(1, 0) line in the absence of the field. Scanning the laser frequency around the resonance frequency of these lines we measured small polarization changes caused by the Voigt effect. Comparing the measured profiles of the magnetically induced lines with the theoretical expression for the Voigt effect we concluded that the transitions were induced by magnetic perturbation to the lower level triplet, which caused mixing among the X-3 Sigma(g)(-), states. (C) 1997 Academic Press.