Spectroscopy of the ⁸⁵Rb 4 D3/2 state for hyperfine-structure determination

Abstract

We report a measurement of the hyperfine-structure constants of the 85Rb 4D3/2 state using two-photon optical spectroscopy of the 5S1/2 →4D3/2 transition. The spectra are acquired by measuring the transmission of the low-power 795-nm lower-stage laser beam through a cold-atom sample as a function of laser frequency, with the frequency of the upper-stage 1476-nm laser fixed. All 4 hyperfine components of the 4D3/2 state are well-resolved in the experimental data. The dominant systematic is the light shift from the 1476-nm laser, which is addressed by extrapolating line positions measured for a set of 1476-nm laser powers to zero laser power. The analysis of our experimental data yields both the magnetic-dipole and electric-quadrupole constants for the 85Rb 4D3/2 level, without using earlier hyperfine measurements of other atomic levels. The respective results, A=7.419(35) MHz and B=4.19(19) MHz, are discussed in context with previous works. Our investigation may be useful for optical atomic clocks for precision metrology and emerging atom-based quantum technologies, all-infrared excitation of Rb Rydberg levels, and molecular physics.