| Abstract: | A simple theoretical analysis, based on the classical theory of the transmission of polarized light through a polarizing medium, has been developed to examine the factors determining the intensity of resonance radiation transmitted by a magnetized atomic vapour interposed between a pair of crossed polarizers. In common with other studies, this analysis predicts a quadratic dependence of the transmitted intensity on atom concentration but in addition, indicates that even at low atom concentrations differential absorption (dichroism) may make a significant addition to the transmitted intensity arising from differential refraction (birefringence). Further, by introducing a small angular off-set between the crossed polarizers, the concentration dependence of the transmitted intensity at low concentration may be increased and linearized. Experiments using a flame-generated atomic vapour of silver with a silver hollow cathode lamp or deuterium lamp as light source confirmed these predictions. When a strong magnetic field (9.75 kG) was used, a detection limit of 0.3 ppm (= μg/ml) for silver, with a near linear response up to 20 ppm was obtained. |
