A few analytical expressions for the observables in a quantum beat experiment is derived, which can be used to describe the experimental results and to obtain the fs splitting in sodium D states. The, change of the n2D states of sodium atoms in a weak electric field is also discussed.
We report the first observation of zero-field quantum beats in the electron-impact excitation of an atomic state. The effect has been observed in electron-photon coincidence experiments on the 32P state in sodium. The beats arise from the influence of the hyperfine structure in the J=23 level of the excited state.
Pulsed dye lasers are used to excite sodium atoms into a coherent superposition of high Rydberg nd(2D23,2D25) states. Analysis of the field ionization behavior of these atoms reveals the time evolution of the superposition state. Rapid application of a weak electric field projects different components of the superposition state onto states having identifiably different field ionization behavior. Analysis of the signal from subsequent field ionization as a function of the time of weak-field application reveals fine-structure quantum beats. These beats result from the time development of the original superposition state. Measurements of the fine-structure quantum beat frequency are presented for the principal quantum numbers n=32,34,35,36,38,and40.
levels of atomic sodium using ultrashort laser pulses in a stepwise excitation scheme. Two broadband femtosecond laser pulses are used to excite the 6S level from the 3S ground level in sodium vapor. The first one is simultaneously resonant with the D1 and D2 lines of the 3S→3P transition, and the second one with the 3P→6S transition. The delay between the two pulses is scanned in order to probe the dephasing between the two excited intermediate levels. Quantum beating is observed by monitoring the fluorescence signals at 330 nm and 515 nm, namely transition 4P→3S and 6S→3P, respectively. Signals are compared to a semi-classical model that reproduces the oscillations with a very good agreement.