We demonstrate a technique for frequency measurements of atomic transitions with a precision of 30 kHz. The frequency is measured with a ring-cavity resonator whose length is calibrated against a reference laser locked to the <i>D</i><sub>2</sub> line of <sup>87</sup>Rb , the frequency of which is known with 10-kHz accuracy. We have used this method to measure the hyperfine structure in the 5<i>P</i><sub>3/2</sub> state of <sup>85</sup>Rb . We obtain precise values for the hyperfine constants, <i>A</i>=25.041(6) MHz and <i>B</i>=26.013(25)MHz , and a value of 77.992(20) MHz for the isotope shift in the <i>D</i><sub>2</sub> line.
© 2003 Optical Society of America
Ayan Banerjee, Dipankar Das, and Vasant Natarajan, "Precise frequency measurements of atomic transitions by use of a Rb-stabilized resonator," Opt. Lett. 28, 1579-1581 (2003)