Strongest Magnetically Induced Transitions in Alkali Metal Atoms with nuclear spin $3/2$

Abstract

The probabilities of atomic transitions Fe−Fg = ±2 between a ground Fg and an excited Fe level of D2 line of any alkali metal atom are zero when no external magnetic field is applied. In an external magnetic field in the range 0.1 − 3 kG, the probabilities of these transitions called magnetically induced (MI) are highly modified. For these MI transitions, we have previously exhibited the following rule: the probabilities of MI transitions with ∆F = +2 are maximal when using σ +polarized laser radiation, while the probabilities of MI transitions with ∆F = −2 are maximal when using σ − -polarized laser radiation. This difference has been termed Type 1 Magnetically Induced Circular Dichroism (MCD1). It is demonstrated for the first time that for alkali atoms with a nuclear spin I = 3/2 ( 87 Rb, 39 K, 23 Na, 7 Li) in magnetic fields > 100 G, the probability of the strongest σ + MI transition of the group Fg = 1 → Fe = 3 ′ (transition |1, −1 → |3 ′ , 0 ′ ) is about 4 times higher than the probabilities of the strongest MI σ − -transitions |1, −1 → |3 ′ , −2 ′ and |2, +1 → |0 ′ , 0 ′ . These properties make the σ + MI transition |1, −1 → |3 ′ , 0 ′ an interesting candidate for the study of magneto-optical processes in strong magnetic fields.