The spectrum of resonance fluorescence for Rydberg autoionization in a laser field has been considered. The spectral form for various ratios between the problem parameters has been investigated.
We consider a single-photon bound–bound and bound–free transitions induced by short, coherent laser pulses. Fluorescence energy spectra are calculated. In the case of the fluorescence to a side level, a number of analytic results are presented. For the resonance-fluorescence case the compact Bloch-like equations are derived for the ionization to an autoionization resonance and numerically analyzed. The multipeak structure of the spectra previously found in the simplified models is shown to be a universal feature. The number of maxima of the spectrum increases with the area of the pulse.
The fluorescence produced by an autoionizing state under strong pumping by a coherent laser field is considered. It is shown how the spectrum of emitted photons and the total number of photons are related to the two-time and single-time atomic expectation values, and explicit expressions are derived for them. Numerical results for the time development of the number of photons ejected are presented for finite times and in the long-time limit. The photon spectra are shown to exhibit ac Stark splitting of the states involved. The spectrum is a doublet for transitions to a stable final state and a triplet for transitions connected back to the initial, strongly driven state. The decay of an autoionizing state in the absence of a laser driving field is considered, and the square of the Fano q value is interpreted as the ratio of two decay rates.