Formation of very-low-energy states crossing the ionization threshold of argon atoms in strong mid-infrared fields
| Autor: | Joachim Ullrich, Burgdörfer, Joachim, M. G. Pullen, Xiao-Min Tong, Robert Moshammer, Michael Hemmer, Matthias Baudisch, Jens Biegert, Arne Senftleben, Benjamin Wolter, Christoph Lemell, Claus Dieter Schröter |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | ResearcherID |
| ISSN: | 1094-1622 1050-2947 |
| Popis: | Atomic ionization by intense mid-infrared (mid-IR) pulses produces low electron energy features that the strong-field approximation, which is expected to be valid in the tunneling ionization regime characterized by small Keldysh parameters ($\gamma \ll 1$), cannot describe. These features include the low-energy structure (LES), the very-low-energy structure (VLES), and the more recently found zero-energy structure (ZES). They result from the interplay between the laser electric field and the atomic Coulomb field which controls the low-energy spectrum also for small $\gamma$. In the present joint experimental and theoretical study we investigate the vectorial momentum spectrum at very low energies. Using a reaction microscope optimized for the detection of very low energy electrons, we have performed a thorough study of the three-dimensional momentum spectrum well below 1 eV. Our measurements are complemented by quantum and classical simulations, which allow for an interpretation of the LES, VLES and of the newly identified ZES in terms of two-dimensional Coulomb focusing and recapture into Rydberg states, respectively. Comment: 18 pages, 7 figures |
| Databáze: | OpenAIRE |
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