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Optical frequency measurements of 6s2S1/2 – 6p2P1/2 (D1) transitions in 133Cs and their impact on the fine-structure constant



Vladislav Gerginov, K Calklins, Carol Tanner, John J. McFerran, Scott A. Diddams, A Bartels, Leo W. Hollberg


High resolution laser spectroscopy of 6s2S1/2 – 6p2P1/2 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


Gerginov, V. , Calklins, K. , Tanner, C. , McFerran, J. , Diddams, S. , Bartels, A. and Hollberg, L. (2006), Optical frequency measurements of 6s<sup>2</sup>S<sub>1/2</sub> &#8211; 6p<sup>2</sup>P<sub>1/2</sub> (D1) transitions in <sup>133</sup>Cs and their impact on the fine-structure constant, Physical Review A (Atomic, Molecular and Optical Physics), [online], (Accessed June 6, 2023)
Created March 8, 2006, Updated February 17, 2017