Anomalous depolarization of the 5p 2P3/2→8p 2Pj′ transitions in atomic 87Rb -: art. no. 012503

Measurements of the linear polarization degree of the 5p P-2(3/2)-->8p P-2(j') transitions (j' = 1/2,3/2) in atomic Rb-87 are reported. The radiative transitions are electric-dipole forbidden, but electric-quadrupole allowed. In addition, because of the relatively strong spin-orbit interaction in Rb, the p-p transitions can acquire a magnetic-dipole transition strength that may be a measurable fraction of the electric-quadrupole strength. The polarization measurements can generally provide a different and sensitive way to extract the relative transition strengths. We have measured the linear polarization degree of the 5p P-2(3/2)-->8P P-2(j') transitions over a wide range of Rb density. We report here observations of a different depolarization effect, whereby the measured polarization of the 5s S-2(1/2)-->5p P-2(3/2)-->8p P-2(1/2) transition increases, while that for the 5s S-2(1/2)-->5p P-2(3/2) -8p P-2(3/2) transition decreases with increasing Rb density. The behavior is attributed to strong laser field effects associated with the 5s S-2(1/2)-->5P P-2(3/2) resonance transition.