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Transitions Fe − Fg = ΔF = ±2 between the excited and ground levels of the hyperfine structure of the Cs D2 atomic line in an external magnetic field of 300–3000 G have been studied for the first time with the use of σ+ and σ− circularly polarized radiation. Selection rules forbid these transitions in zero magnetic field. At the same time, the probabilities of these transitions in a magnetic field increase significantly; for this reason, we refer to these transitions as magnetically induced transitions. The following rule has been found for the intensities of 24 magnetically induced Fg = 3 → Fe = 5 and Fg = 4 → Fe = 2 transitions: the intensities of magnetically induced transitions with ΔF = +2 are maximal (the number of such magnetically induced transitions is also maximal) in the case of σ+ polarized radiation, whereas the intensities of magnetically induced transitions with ΔF = −2 are maximal (the number of such transitions is also maximal) in the case of σ− σ+ and σ− polarized radiation can reach several orders of magnitude; i.e., anomalous circular dichroism is observed. For an experimental test, absorption spectra of a Cs-filled nanocell with the thickness equal to half the wavelength of resonant laser radiation = 852 nm have been analyzed in order to separately detect magnetically induced transitions. The experiment is in good agreement with the theory. Possible applications have been discussed. [ABSTRACT FROM AUTHOR]

Electromagnetically induced transparency (EIT) resonance in strong magnetic fields of up to 1.7 kG has been investigated with the use of a 30-μm cell filled with an atomic rubidium vapor and neon as a buffer gas. The EIT resonance in the Λ system of the D line of Rb atoms has been formed with the use of two narrowband (∼1 MHz) 795-nm diode lasers. The EIT resonance in a longitudinal magnetic field is split into five components. It has been demonstrated that the frequencies of the five EIT components are either blue- or red-shifted with an increase in the magnetic field, depending on the frequency ν of the probe laser. In has been shown that in both cases the Rb atoms enter the hyperfine Paschen-Back regime in magnetic fields of >1 kG. The hyperfine Paschen-Back regime is manifested by the frequency slopes of all five EIT components asymptotically approaching the same fixed value. The experiment agrees well with the theory. [ABSTRACT FROM AUTHOR]