Description
Motivated by the recent experimental work of Goulielmakis et
al. on real-time observation of electron motion in the
valence 4p shell of krypton atoms [1], we will present the
theory for the ionization of arbitrary states of atoms in
strong circularly polarized laser fields. It is commonly
assumed that strong-field ionization in low-frequency laser
field is an adiabatic process. Therefore, one does not
expect to generate electronic ring currents in ions during
ionization in the low-frequency fields. To check this
assumption, we revisit the theory of strong-field ionization
developed by Perelomov, Popov, and Terent’ev (PPT) [2,3].
The original PPT theory includes explicit results for
ionization of s-orbitals by circularly or in general
elliptically polarized laser fields. We extend the PPT
approach to p0, p+ and p- orbitals of atoms in circularly
polarized field. This allows us to address the question on
the asymmetry in ionizing the ring-current carrying p+ and
p- orbitals by the right (or left) circular polarization,
thus characterizing the currents that can be induced by
non-adiabatic ionization.
[1] E. Goulielmakis, Z.-H. Loh, A. Wirth, R. Santra, N.
Rohringer, V. S. Yakovlev, S. Zherebtsov, T. Pfeifer, A. M.
Azzeer, M. F. Kling, S. R. Leone, F. Krausz, Real-time
observation on valence electron motion, Nature 466, 739 (2010)
[2] A. M. Perelomov, V. S. Popov, M. V. Terent’ev,
Ionization of atoms in an alternating electric field, Soviet
Physics JETP 23, 924 (1966)