Velocity-selective spectroscopy measurements of Rydberg fine structure states in a hot vapor cell**Project supported by the National Natural Science Foundation of China (Grant Nos. 61475091 and 61227902), the National Key Research and Development Program of China (Grant No. 2017YFA0304502), and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi, China (Grant No. 2017101).

Abstract

A velocity-selective spectroscopy technique for studying the spectra of Rydberg gases is presented. This method provides high-resolution spectrum measurements. We present experimental results for a ladder system 6S1/2 → 6P3/2 →nS(D) electromagnetically-induced transparency involving highly-excited Rydberg states. Based on a radio-frequency modulation technique, we measure the hyperfine structure splitting of intermediate states and the fine structure splitting of Rydberg states in a room temperature 133Cs vapor cell. The experimental data and theoretical predictions show excellent agreement.