Abstract

The probabilities of atomic transitions ${F_e} - {F_g} = \pm 2$ between a ground ${F_g}$ and an excited ${F_e}$ level of the ${D_2}$ line of any alkali metal atom are zero when no external magnetic field is applied. In an external magnetic field in the range of 0.1–3 kG, the probabilities of these transitions called magnetically induced (MI) are highly modified. For MI transitions, we previously exhibited the following rule: the probabilities of MI transitions with $\Delta F = + 2$ are maximal when using ${\sigma ^ +}$-polarized laser radiation, while the probabilities of MI transitions with $\Delta F = - 2$ are maximal when using ${\sigma ^ -}$-polarized laser radiation. This difference has been termed type 1 MI circular dichroism. It is demonstrated for the first time, to our knowledge, that for alkali atoms with a nuclear spin $I = 3/2$ ($^{87}{\rm{Rb}}$, $^{39}{\rm{K}}$, $^{23}{\rm{Na}}$, $^7{\rm{Li}}$) in magnetic fields ${\gt}100\;{\rm{G}}$, the probability of the strongest ${\sigma ^ +}$ MI transition of the group ${F_g} = 1 \to {F_e} = 3^\prime $ (transition $|1, - 1\rangle \to |3^\prime ,0^\prime \rangle$) is about four times higher than the probabilities of the strongest MI ${\sigma ^ -}$-transitions $|1, - 1\rangle \to |3^\prime , - 2^\prime \rangle$ and $|2, + 1\rangle \to |0^\prime ,0^\prime \rangle$. These properties make the ${\sigma ^ +}$ MI transition $|1, - 1\rangle \to |3^\prime ,0^\prime \rangle$ an interesting candidate for the study of magneto-optical processes in strong magnetic fields.

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