title: Probing nonadiabatic effects in strong-field tunnel ionization.
abstract: We investigate experimentally the validity of proposed theories extending the tunneling approximation towards the multiphoton regime in strong-field ionization of helium. We employ elliptically polarized laser pulses and demonstrate how the influence of the ion potential on the released electron encoded in the measured observable provides the desired sensitivity to detect nonadiabatic effects in tunnel ionization. Our results show that for a large intensity range the proposed nonadiabatic theories contradict the experimental trends of the data, while adiabatic assumptions are confirmed.
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Boge
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Cirelli
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: A S
authors.initials: AS
authors.lastname: Landsman
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Heuser
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Ludwig
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Maurer
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Weger
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Gallmann
authors.affiliation: Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Keller