Effect of electric fields on the decay branching ratio of {sup 1}P{sup e} doubly excited states in helium measured by time-resolved fluorescence
- Jozef Stefan Institute, P. O. Box 3000, SI-1001 Ljubljana (Slovenia)
- LCP-MR, Universite Pierre et Marie Curie 6 and CNRS (UMR 7614), 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)
- Sincrotrone Trieste, I-340 12 Trieste (Italy)
- INFM-TASC, Padriciano 99, I-340 12 Trieste (Italy)
- Dipartimento di Chimica, Universita di Roma 'La Sapienza' and INFM Unit, 00185 Rome (Italy)
We have measured the lifetimes of {sup 1}P{sup e} (n=9-12) doubly excited states in static electric fields (1-6 kV/cm) by observing the decay of the fluorescence signal as a function of time. The effects of the field on these helium states below the second ionization threshold are twofold: their excitation becomes possible due to the Stark mixing with the optically allowed {sup 1}P{sup o} series, and their lifetime is strongly modified by the opening of the autoionization channel, not accessible in zero field. Although the electric field represents only a tiny perturbation of the atomic potential, a substantial shortening of the lifetimes below 100 ps is observed. This is the simplest quantum system where the ratio of autoionization to fluorescence decay probability can be effectively controlled by an electric field of moderate strength.
- OSTI ID:
- 20974675
- Journal Information:
- Physical Review. A, Vol. 74, Issue 5; Other Information: DOI: 10.1103/PhysRevA.74.051404; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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