Magneto-optical Faraday absorption spectra of the CS-D2 line

The magnetic energy level splittings of an atom and the line strength distribution are not influenced by the direction of an applied magnetic field. For the Faraday geometry, however, when the absorption spectra of right (R) or left (L) elliptically (pseudo-circularly) polarized light are measured, a large spectral shift is observed which can not be attributed to the level splittings or the line distribution. In the absence of the incident light, the sigma(+) and sigma(-) transition components are mixed in a complicated way. However, for the case where R is incident, it can, for example, induce a sigma(+) transition for which it is observed that all Zeeman absorption spectral lines sigma(+) in R shift in the same direction in groups, whereas those in L under a sigma(-) transition shift in groups in the other direction. The direction of the shift is inverted when the magnetic field direction is reversed. The shift is not a level shift but a virtual frequency shift as observed from the perspective of the polarized light itself when interacting with the atoms which are precessing around the magnetic field. (C) 1998 Elsevier Science Ltd. All rights reserved.