title: Separation of recollision mechanisms in nonsequential strong field double ionization of Ar: the role of excitation tunneling.
abstract: Vector momentum distributions of two electrons created in double ionization of Ar by 25 fs, 0.25 PW/cm(2) laser pulses at 795 nm have been measured using a "reaction microscope." At this intensity, where nonsequential ionization dominates, distinct correlation patterns are observed in the two-electron momentum distributions. A kinematical analysis of these spectra within the classical "recollision model" revealed an (e,2e)-like process and excitation with subsequent tunneling of the second electron as two different ionization mechanisms. This allows a qualitative separation of the two mechanisms demonstrating that excitation-tunneling is the dominant contribution to the total double ionization yield.
authors.affiliation: Universität Freiburg, Hermann-Herder-Strasse 3, D-79104 Freiburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Feuerstein
authors.forename: R
authors.initials: R
authors.lastname: Moshammer
authors.forename: D
authors.initials: D
authors.lastname: Fischer
authors.forename: A
authors.initials: A
authors.lastname: Dorn
authors.forename: C D
authors.initials: CD
authors.lastname: Schröter
authors.forename: J
authors.initials: J
authors.lastname: Deipenwisch
authors.forename: J R
authors.initials: JR
authors.lastname: Crespo Lopez-Urrutia
authors.forename: C
authors.initials: C
authors.lastname: Höhr
authors.forename: P
authors.initials: P
authors.lastname: Neumayer
authors.forename: J
authors.initials: J
authors.lastname: Ullrich
authors.forename: H
authors.initials: H
authors.lastname: Rottke
authors.forename: C
authors.initials: C
authors.lastname: Trump
authors.forename: M
authors.initials: M
authors.lastname: Wittmann
authors.forename: G
authors.initials: G
authors.lastname: Korn
authors.forename: W
authors.initials: W
authors.lastname: Sandner