Measurements of fine and hyperfine structures in highly excited Rydberg atoms

Fine and hyperfine structures of Rydberg states in indium have been studied by double-resonance spectroscopy using laser and microwave. The nf2F5/2,7/2 Rydberg series are observed for n=30-81. The quantum defects of the 2F5/2 and 2F7/2 series and the fine-structure splitting of the 5d2D level are determined by means of least-squares fitting of the experimental data to Rydberg-Ritz Formula. The determined term values show that all the fine-structure splitting of the F states is inverted. The microwave transition of 38 p → 39 s exhibits that the hyperfine splitting of the 39 s2S1/2 level is 11.4(10) MHz which has been measured for the first time for such a highly excited Rydberg state. (author)