The Spatial Region of Photoionization in a Strong Laser Field

J.H. Bauer Katedra Fizyki Teoretycznej Uniwersytetu Łódzkiego, Pomorska 149/153, 90-236 Łódź, Poland

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Received: 2 07 2008;

In the framework of the Keldysh-Faisal-Reiss theory in the velocity gauge we investigate the magnitude of the space region, where photoionization in a strong laser field takes place. We find substantial differences between the short-range and the long-range (Coulomb) potentials, and between linear and circular polarizations of incident radiation. It appears that only for the initial state in the Coulomb potential the region of space, where ionization is held, expands significantly with increasing intensity for a typical optical frequency and non-relativistic but strong circularly polarized laser field. As a result of our considerations, we suggest to modify the idea of Reiss and Krainov of a certain simple Coulomb correction to the Volkov wave function. We show that photoionization rate calculated for the H(1s) atom, using our approach, is in better agreement with other theoretical results for moderately strong circularly polarized laser field.

DOI: 10.12693/APhysPolA.114.739 PACS numbers: 32.80.Rm, 42.50.Hz