Physical Review Letters

Electric-field–induced interferences in autoionizing resonances

E. B. Saloman, J. Cooper, Daniel E. Kelleher

Published Jul 8, 1985• 36 citations

Abstract

We have observed the effect of electric fields on the 5d9p ${}^{3}$${P}_{1}$\ifmmode^\circ\else\textdegree\fi{} barium resonance above the first ionization threshold. This relatively broad autoionizing level is nearly degenerate with a much narrower level of opposite parity. At moderate fields the sharp level produces an interference dip in the broad level. At higher fields the interference eventually gives rise to two split components. The results are in good agreement with a nonperturbative theory, summarized in this letter.

DOI: 10.1103/physrevlett.55.193

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Physical Review Letters

Electric-field–induced interferences in autoionizing resonances

E. B. Saloman, J. Cooper, Daniel E. Kelleher

Published Jul 8, 1985• 36 citations

Publisher

Abstract

We have observed the effect of electric fields on the 5d9p

{}^{3}$${P}_{1}

\ifmmode^\circ\else\textdegree\fi{} barium resonance above the first ionization threshold. This relatively broad autoionizing level is nearly degenerate with a much narrower level of opposite parity. At moderate fields the sharp level produces an interference dip in the broad level. At higher fields the interference eventually gives rise to two split components. The results are in good agreement with a nonperturbative theory, summarized in this letter.

DOI: 10.1103/physrevlett.55.193

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Photoionization spectroscopy of Yb I from the 6s7sS01 state in the presence of a static electric field

Christophe Blondel, René-Jean Champeau, Christian Delsart

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Christian Delsart, Jean-Claude Keller

The first detailed observation of the perturbations by an electric field of the Rydberg autoionizing resonances of a rare-gas atom is reported. The Stark spectroscopy of autoionizing Rydberg states converging to the second ionization limit $4{p}^{5}^{2}P_{\frac{1}{2}}^{o}$ in Kr I is performed in an atomic beam with the use of a two-step laser excitation from the $4{p}^{5}5s{[\frac{3}{2}]}_{2}^{0}$ metastable state. In addition to the verification of the ${({n}^{*})}^{\ensuremath{-}3}$ dependence of the zero-field width of two autoionizing series and of the linear dependence of the Stark-manifold splittings with the electric field, we have observed an ${(n)}^{0.7}$ law for the dependence of the Stark-manifold splitting along the series, an important narrowing and dissymmetrization of the $n{d}^{\ensuremath{'}}$ resonances, and a nonlinear-field behavior of Stark-manifold components in the vicinity of the first anticrossing. Discussions are carried out with the use of the recent work on Rydberg-Stark spectroscopy and on autoionizing states in two-electron atoms.The first detailed observation of the perturbations by an electric field of the Rydberg autoionizing resonances of a rare-gas atom is reported. The Stark spectroscopy of autoionizing Rydberg states converging to the second ionization limit $4{p}^{5}^{2}P_{\frac{1}{2}}^{o}$ in Kr I is performed in an atomic beam with the use of a two-step laser excitation from the $4{p}^{5}5s{[\frac{3}{2}]}_{2}^{0}$ metastable state. In addition to the verification of the ${({n}^{*})}^{\ensuremath{-}3}$ dependence of the zero-field width of two autoionizing series and of the linear dependence of the Stark-manifold splittings with the electric field, we have observed an ${(n)}^{0.7}$ law for the dependence of the Stark-manifold splitting along the series, an important narrowing and dissymmetrization of the $n{d}^{\ensuremath{'}}$ resonances, and a nonlinear-field behavior of Stark-manifold components in the vicinity of the first anticrossing. Discussions are carried out with the use of the recent work on Rydberg-Stark spectroscopy and on autoionizing states in two-electron atoms.

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4{f}^{14}6s7s^{1}S_{0}

which was populated by a two-step excitation. Broad modulations (in $\ensuremath{\pi}$ polarization) and Stark resonances in the vicinity of the zero-field ionization limit are interpreted satisfactorily as in the case of alkali atoms. However, the photoionization spectra are deeply affected by the presence of two perturbing levels belonging to the configuration

4{f}^{13}5{d}^{2}6s

. This phenomenon is explained by strong interference effects between the structured Stark continuum and the field-induced autoionizing states corresponding to the doubly excited levels.

We report the effects of static electric fields on the doubly excited

6{p}_{\frac{1}{2}}\mathrm{nl}

states of barium in the region

{n}^{*}=12

. Using a three-step laser excitation scheme we have measured the electric-field dependence of the positions and autoionization widths of the $6{p}_{\frac{1}{2}}\ensuremath{-}17s,16p,15d,12l (l=4\ensuremath{-}10),12f, \mathrm{and} 16s$ states at field values of up to 4.92 kV/cm. The photoexcitation spectra of the autoionizing states exhibit interference effects which are well understood and provide a better understanding of the character of these states in electric fields. The systematic study of the spectra and positions allows us to explain the field dependence of the autoionization widths in terms of electric-field mixing of the discrete portions of the auoionizing states. The relationship of these effects to dielectronic recombination rates of ions and electrons in plasma microfields is discussed.

4{p}^{5}5s{[\frac{3}{2}]}_{2}^{0}

metastable state. In addition to the verification of the ${({n}^{*})}^{\ensuremath{-}3}$ dependence of the zero-field width of two autoionizing series and of the linear dependence of the Stark-manifold splittings with the electric field, we have observed an

{(n)}^{0.7}

law for the dependence of the Stark-manifold splitting along the series, an important narrowing and dissymmetrization of the $n{d}^{\ensuremath{'}}$ resonances, and a nonlinear-field behavior of Stark-manifold components in the vicinity of the first anticrossing. Discussions are carried out with the use of the recent work on Rydberg-Stark spectroscopy and on autoionizing states in two-electron atoms.