Atomic stabilization in intense laser fields |
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| Morten Førre | |
| Unversity of Bergen | |
| For the simplest atomic system in nature, hydrogen, which has a binding energy of 13.6 eV, absorption of a single photon with an energy exceeding this value will induce direct breakup of the system. With increasing photon flux, additional photons can be absorbed, giving rise to multiphoton processes and above-threshold ionization (ATI). From perturbation theory calculations a general increase in breakup probability with intensity of the imposed radiation field is expected. It therefore came as a big surprise to many when, more than 20 years ago, theoretical studies of atomic hydrogen in ultraintense, high-frequency laser fields showed some evidence of the complete opposite scenario, i.e., that the atom may eventually become more stable as the ionizing radiation gets stronger. This rather counterintuitive phenomenon, called atomic stabilization, has since then been studied extensively. Up to present times, experimental confirmation of atomic stabilization in tightly bound atomic systems, such as neutral atoms in their ground state, has been obstructed due to lack of the laser technology required to produce the necessary conditions. The possibility of observing the phenomenon in excited atomic states was pointed out early, and the first experimental signature of atomic stabilization in low-lying Rydberg atoms was reported in 1993.
In this talk I will give an overview over our recent studies on the problem of atomic stabilization in atomic hydrogen, helium and Rydberg atoms. |