Study of the 5p3/2 -> 6p3/2 electric dipole forbidden transition in atomic rubidium using optical-optical double resonance spectroscopy

摘要

Direct evidence of excitation of the 5p3/2 -> 6p3/2 electric dipole forbiddentransition in atomic rubidium is presented. The experiments were performed in aroom temperature rubidium cell with continuous wave extended cavity diodelasers. Optical-optical double resonance spectroscopy with counterpropagatingbeams allows the detection of the non-dipole transition free of Dopplerbroadening. The 5p3/2 state is prepared by excitation with a laser locked tothe maximum F cyclic transition of the D2 line, and the forbidden transition isproduced by excitation with a 911 nm laser. Production of the forbiddentransition is monitored by detection of the 420 nm fluorescence that resultsfrom decay of the 6p3/2 state. Spectra with three narrow lines (~ 13 MHz FWHM)with the characteristic F - 1, F and F + 1 splitting of the 6p3/2 hyperfinestructure in both rubidium isotopes were obtained. The results are in very goodagreement with a direct calculation that takes into account the 5s -> 5p3/2preparation dynamics, the 5p3/2 -> 6p3/2 non-dipole excitation geometry and the6p3/2 -> 5s1/2 decay. The comparison also shows that the electric dipoleforbidden transition is a very sensitive probe of the preparation dynamics.