title: Sensitivity of nonlinear photoionization to resonance substructure in collective excitation.
abstract: Collective behaviour is a characteristic feature in many-body systems, important for developments in fields such as magnetism, superconductivity, photonics and electronics. Recently, there has been increasing interest in the optically nonlinear response of collective excitations. Here we demonstrate how the nonlinear interaction of a many-body system with intense XUV radiation can be used as an effective probe for characterizing otherwise unresolved features of its collective response. Resonant photoionization of atomic xenon was chosen as a case study. The excellent agreement between experiment and theory strongly supports the prediction that two distinct poles underlie the giant dipole resonance. Our results pave the way towards a deeper understanding of collective behaviour in atoms, molecules and solid-state systems using nonlinear spectroscopic techniques enabled by modern short-wavelength light sources.
authors: European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany.
authors: T
authors: T
authors: Mazza
authors: 1] Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany [2] Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany.
authors: A
authors: A
authors: Karamatskou
authors: 1] European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany [2] Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors: M
authors: M
authors: Ilchen
authors: 1] European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany [2] Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany.
authors: S
authors: S
authors: Bakhtiarzadeh
authors: 1] European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany [2] Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany.
authors: A J
authors: AJ
authors: Rafipoor
authors: CNR Istituto di Struttura della Materia, CP10, I-00016 Monterotondo Scalo, Italy.
authors: P
authors: P
authors: O'Keeffe
authors: School of Physical Sciences and NCPST, Dublin City University, Dublin 9, Ireland.
authors: T J
authors: TJ
authors: Kelly
authors: School of Physical Sciences and NCPST, Dublin City University, Dublin 9, Ireland.
authors: N
authors: N
authors: Walsh
authors: School of Physical Sciences and NCPST, Dublin City University, Dublin 9, Ireland.
authors: J T
authors: JT
authors: Costello
authors: European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany.
authors: M
authors: M
authors: Meyer
authors: 1] Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany [2] Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany.
authors: R
authors: R
authors: Santra