Journal of Experimental and Theoretical Physics
The break of L-S coupling and the double Stark resonance in the spectrum of 36P → 37P two-photon transition in Rydberg atoms of sodium
I. I. Ryabtsev, Denis B. Tretyakov
Abstract
New results are presented of an experimental investigation of the spectrum of 36 P → 37 P two-photon microwave transition in Rydberg atoms of sodium in a constant electric field. Depending on the conditions of excitation of the initial 36 P state (the constant electric field is switched on either before or after the exciting laser pulse) and polarization of laser radiation, a strong variation is observed of the amplitudes of individual two-photon transitions between the fine-structure Stark components of the 36 P and 37 P states. This effect is an analog of the Paschen-Back effect in a strong magnetic field and is due to the break of L-S coupling and to the variation of the wave functions of Rydberg electrons in an electric field. It is also found that the break of L-S coupling affects considerably the shape of double Stark resonance arising upon intersection of the virtual intermediate level of two-photon transition with the real intermediate 37 S level.