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Phys. Rev. A 58, R46 - R49 (1998)

Population trapping and laser-induced continuum structure in helium: Experiment and theory

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T. Halfmann, L. P. Yatsenko *, M. Shapiro †, B. W. Shore ‡, and K. Bergmann
Fachbereich Physik der Universität, 67653 Kaiserslautern, Germany

Rapid Communication Received 25 March 1998

We report the observation of laser-induced structure (LICS) in the flat photoionization continuum of helium. The structure is a strong and spectrally sharp resonance, showing both enhanced and diminished ionization (a Beutler-Fano profile). Our observations show, in an otherwise unstructured continuum, pronounced ionization suppression (as much as 70%), which is due to population trapping associated with LICS. We also show the effect of dynamic Stark shifts upon the LICS profile. A discussed theoretical model, incorporating significant dynamic Stark shifts, gives a quantitatively accurate description of the line profile for a wide range of pulse intensities.


©1998 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.58.R46
DOI: 10.1103/PhysRevA.58.R46
PACS: 42.50.Hz, 32.80.Fb, 32.80.Qk

* Permanent address: Institute of Physics, Ukrainian Academy of Sciences, Prospekt Nauki 46, Kiev-22, 252650, Ukraine.
† Permanent address: Department of Chemical Physics, The Weizmann Institute of Science, Rehovot, Israel 76100.
‡ Permanent address: Lawrence Livermore National Laboratory, Livermore, CA 94550.

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