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Physical Review Letters

Autoionization Inhibited by Internal Interferences

Jörg Neukammer, Herbert H. Rinneberg, G. Jönsson, William E. Cooke, H. Hieronymus, Andreas Sebastian Konig, K. Vietzke, H. Spinger-Bolk

Published Nov 4, 1985• 53 citations
Publisher

Abstract

We have measured the linewidths of ${[5{d}_{\frac{3}{2}}{n}_{2}{d}_{\frac{3}{2}}]}_{J=0}$ autoionizing Rydberg states of barium with principal quantum numbers ranging between ${n}_{2}=14$ and ${n}_{2}=100$. Dramatic deviations of the autoionization rates from the normal ${n}_{2}^{*\ensuremath{-}3}$ scaling law have been observed. Whereas the ${[5{d}_{\frac{3}{2}}60{d}_{\frac{3}{2}}]}_{J=0}$ level exhibits a linewidth $\ensuremath{\Gamma}$ (FWMH) as low as 6 MHz, higher (${n}_{2}\ensuremath{\approx}80$) members of this series are broadened up to 5 GHz. Autoionization is inhibited for principal quantum numbers ${n}_{2}\ensuremath{\approx}60$ because of configuration interaction between the ${[5{d}_{\frac{3}{2}}{n}_{2}{d}_{\frac{3}{2}}]}_{J=0}$ and ${[5{d}_{\frac{5}{2}}{n}_{3}{d}_{\frac{5}{2}}]}_{J=0}$ Rydberg series. This causes the state at ${n}_{2}=60$ to be metastable.

DOI
10.1103/physrevlett.55.1979

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We report the first observation of hyperfine structure and isotope shift in autoionizing states. This structure was investigated in the $5{d}_{\frac{3}{2}}\mathrm{nf} J=4,5(n=36\ensuremath{-}40)$ barium Rydberg series, excited from the recently localized metastable $5{d}^{2}^{1}G_{4}$ level. An isotope-selective detection method was used in a cw laser spectroscopic experiment on a collimated atomic beam. The experimental data provide valuable additional information for the analyses of these doubly excited series.
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