title: Visualizing the coupling between red and blue stark states using photoionization microscopy.
abstract: In nonhydrogenic atoms in a dc electric field, the finite size of the ionic core introduces a coupling between quasibound Stark states that leads to avoided crossings between states that would otherwise cross. Near an avoided crossing, the interacting states may have decay amplitudes that cancel each other, decoupling one of the states from the ionization continuum. This well-known interference narrowing effect, observed as a strongly electric field-dependent decrease in the ionization rate, was previously observed in several atoms. Here we use photoionization microscopy to visualize interference narrowing in helium atoms, thereby explicitly revealing the mechanism by which Stark states decay. The interference narrowing allows measurements of the nodal patterns of red Stark states, which are otherwise not observable due to their intrinsic short lifetime.
authors.affiliation: FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: A S
authors.initials: AS
authors.lastname: Stodolna
authors.affiliation: Institut Lumiére Matiére, Université Lyon 1, CNRS, UMR 5306, 10 rue Ada Byron, 69622 Villeurbanne Cedex, France.
authors.forename: F
authors.initials: F
authors.lastname: Lépine
authors.affiliation: Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.
authors.forename: T
authors.initials: T
authors.lastname: Bergeman
authors.affiliation: Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: F
authors.initials: F
authors.lastname: Robicheaux
authors.affiliation: FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Gijsbertsen
authors.affiliation: FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: J H
authors.initials: JH
authors.lastname: Jungmann
authors.affiliation: Institut Lumiére Matiére, Université Lyon 1, CNRS, UMR 5306, 10 rue Ada Byron, 69622 Villeurbanne Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Bordas
authors.affiliation: FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands and Max-Born-Institut, Max Born Straße 2A, D-12489 Berlin, Germany.
authors.forename: M J J
authors.initials: MJ
authors.lastname: Vrakking