Optical frequency measurements of 6s 2S1/2 – 6p 2P1/2 (D1)transitions in 133Cs and their impact on the fine-structure constant
Vladislav Gerginov, K Calklins, B Tanner, John J. McFerran, Scott A. Diddams, Albrecht Bartels, Leo W. Hollberg
High resolution laser spectroscopy of 6s 2S1/2 – 6p 2P1/2 transition (D1 line) in neutral 133Cs is performed in a highly collimated thermal atomic beam using a femtosecond laser frequency comb and narrow linewidth diode laser. The diode laser is offset-locked to a single frequency component of the femtosecond laser frequency comb and probes the optical transitions between selected pairs of ground state and excited state hyperfine components. A photodiode detects the excited state decay fluorescence, and a computerized data acquisition system records the signal. The Doppler shift is eliminated by orienting the laser beam in a direction perpendicular to the atomic beam to within a precision of 5 x 10-6 radians. Optical frequencies for all four pairs of hyperfine components are measured independently from which the D1 line centroid and excited state hyperfine splitting are obtained by least-squares minimization with the ground state splitting as a fixed constraint. We find the D1 line centroid to be fD1 = 335 116 048 748.1(2.4) kHz, and the 6p 2P1/2 state hyperfine splitting to be 1 167 723.6(4.7) kHz. These results in combination with the results of an atom interferometry experiment are used to calculate a new value for the fine-structure constant.
Physical Review A (Atomic, Molecular and Optical Physics)
atomic structure, femtosecond laser frequency comb, fine structure constant, optical frequencies
, Calklins, K.
, Tanner, B.
, McFerran, J.
, Diddams, S.
, Bartels, A.
and Hollberg, L.
Optical frequency measurements of 6s <sup>2</sup>S<sub>1/2</sub> – 6p <sup>2</sup>P<sub>1/2</sub> (D<sup>1</sup>)transitions in <sup>133</sup>Cs and their impact on the fine-structure constant, Physical Review A (Atomic, Molecular and Optical Physics), [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=841931
(Accessed November 29, 2023)