Circular Dichroism of Atomic Transitions of the Rb D1 Line in Magnetic Fields

Abstract

The circular dichroism effect has been investigated for atomic transitions of the Rb D₁ line in magnetic fields of up to 3 kG using circularly polarized σ⁺ and σ⁻ radiation. The process of selective reflection from a 350-nm-thick nanocell has been used, which makes it possible to form narrow atomic lines and observe separately the behavior of individual transitions. Two groups consisting of six (⁸⁵Rb atoms) and four (⁸⁷Rb atoms) transitions are formed in magnetic fields B > 0.5 kG upon σ⁺ and σ⁻ laser excitation. All transitions have been identified. It is shown that the strongest transitions for ⁸⁷Rb and ⁸⁵Rb atoms in magnetic fields of up to several kG are formed under σ⁻ irradiation. A further increase in the magnetic field makes it possible to attain the Paschen–Back regime on a hyperfine structure, for which the probabilities of transitions upon σ⁺ and σ⁻ excitation become identical. The theoretical model and experiment are in good agreement.