Magnetically induced atomic transitions of potassium D$_{2}$-line

Magnetically induced (MI) transitions of the D$_{2}$ line of $^{39}$K atom in an external magnetic field of 10–600 G have been experimentally and theoretically investigated for the first time using circularly polarized $\sigma^{+}$ and $\sigma^{-}$ radiations. According to the selection rules, the transitions between the sublevels of the ground and excited levels of a hyperfine structure with $F_{g}=\Delta F=\pm$ 2 are forbidden in the zero magnetic field, whereas their probabilities increase radically in a magnetic field. For the $F_{g}=1\to F_{e}$ = 3 ($\Delta F$ = +2) and $F_{g}$ = 2 $\to F_{e}$ = 0 MI transitions, the highest probabilities are achieved using the $\sigma^{+}$ and $\sigma^{-}$ radiations, respectively. The atomic transitions have been spectrally resolved using selective reflection of laser radiation from a nanocell filled with potassium atomic vapor, which makes it possible to investigate the behavior of the MI transitions. The experimental and theoretical data are shown to be in good agreement.