title: Nonsequential Double Ionization by Counterrotating Circularly Polarized Two-Color Laser Fields.
abstract: We report on nonsequential double ionization of Ar by a laser pulse consisting of two counterrotating circularly polarized fields (390 and 780 nm). The double-ionization probability depends strongly on the relative intensity of the two fields and shows a kneelike structure as a function of intensity. We conclude that double ionization is driven by a beam of nearly monoenergetic recolliding electrons, which can be controlled in intensity and energy by the field parameters. The electron momentum distributions show the recolliding electron as well as a second electron which escapes from an intermediate excited state of Ar^{+}.
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Eckart
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Richter
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kunitski
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hartung
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Rist
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Henrichs
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Schlott
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.|State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: H
authors.initials: H
authors.lastname: Kang
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Bauer
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Sann
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: L Ph H
authors.initials: LP
authors.lastname: Schmidt
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schöffler
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Jahnke
authors.affiliation: Institut für Kernphysik, Goethe-Universität, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Dörner