STABILIZATION IN THE QUASI-BOUND STARK SPECTRUM

В. В. Колосов

Mikhail Vladimirovich Fedorov, A. M. Movsesian

Ac Stark splitting and ionization broadening of atomic Rydberg levels in a strong electromagnetic field are described. The quasi-energy atomic spectrum is shown to consist of a quasi-continuum plus two sets of narrow quasi-energy levels: weakly split and broadened almost field-free levels and strongly perturbed levels, whose width is a decreasing function of the field strength amplitude. The strong-field asymptotics of the photoelectron spectrum and of the time-dependent total photoionization probability are described. The photoelectron spectrum is shown to have a multipeak structure, and the shape of each peak is shown to be different from the Lorenz shape found earlier. This effect is explained by the contribution of the quasi-continuous quasi-energy spectrum. The same reason explains a partially nonexponential time dependence of the total photoionization probability.

Christian Chardonnet, Francis Jean Penent, Dominique Delande +2 more

We present the experimental evidence of the linear Stark behaviour in an atomic spectrum at low (absolute) electric field strengths on high lying quasi-hydrogenic series of atomic caesium. This is the behaviour which would be observed on hydrogen atoms for any level. It is exhibited here in the 1-15 V/cm range on quasi-hydrogenic atoms, excited, in vapour phase, by a c.w. dye laser to n = 60 Rydberg states. Under these conditions, the core effects are almost negligible compared with the first linear-in-field term in the Stark expansion of the energy.

G. Barry Hillard

The photoionization spectrum of potassium in an external electric field is examined. Detailed studies are made of the strengths, spacing, and polarization dependence of the quasi-bound Stark states lying above E = O. The results are interpreted as the first observation of electric field enhanced collisional depolarization by charged particles. This conclusion is supported by calculations indicating a depolarizing cross section as large as 10-5 cm2 for the conditions of the experiment.

А. А. Корниенко, Elena B. Dunina