We investigated the magnetic-field-induced transition of the oxygen mo
lecule 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 las
er 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 theoretic
al expression for the Voigt effect we concluded that the transitions w
ere induced by magnetic perturbation to the lower level triplet, which
caused mixing among the X-3 Sigma(g)(-), states. (C) 1997 Academic Pr
ess.