Spectral narrowing of the hyperfine signals by recurrent excitation in the excited state of Rb atoms

Summary form only given. To understand the fundamental properties of an atom, precise measurement of the atomic resonance frequency is important. The main factor that restricts the precision is the spectral broadening. Spectral narrowing by recurrent use of free decay signal in magnetic resonance was proposed and demonstrated in the ground state of Rb atoms. In the present report we apply this technique to the measurement of the hyperfine frequency in the excited state. This is a sublevel spectroscopy with recurrent excitation, where the atomic response is iteratively used as the next excitation. The hyperfine spectra of the excited state /sup 2/P/sub 3/2/ of the D/sub 2/ transition in Rb atoms, whose line width is much narrower than the natural line width, was observed and the hyperfine constants of the excited state were determined precisely.