title: Transition from SAMO to Rydberg State Ionization in C60in Femtosecond Laser Fields.
abstract: The transition between two distinct ionization mechanisms in femtosecond laser fields at 785 nm is observed for C60molecules. The transition occurs in the investigated intensity range from 3 to 20 TW/cm2and is visualized in electron kinetic energy spectra below the one-photon energy (1.5 eV) obtained via velocity map imaging. Assignment of several observed broad spectral peaks to ionization from superatom molecular orbitals (SAMOs) and Rydberg states is based on time-dependent density functional theory simulations. We find that ionization from SAMOs dominates the spectra for intensities below 5 TW/cm2. As the intensity increases, Rydberg state ionization exceeds the prominence of SAMOs. Using short laser pulses (20 fs) allowed uncovering of distinct six-lobe photoelectron angular distributions with kinetic energies just above the threshold (below 0.2 eV), which we interpret as over-the-barrier ionization of shallow f-Rydberg states in C60.
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.|State Key Laboratory of Precision Spectroscopy, East China Normal University , Shanghai 200062, China.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Chemistry, University of Liege , B-4000 Liege, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Mignolet
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.|The MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Applied Physics Institute and School of Physics, Nankai University , Tianjin 300457, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.
authors.forename: K J
authors.initials: KJ
authors.lastname: Betsch
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.
authors.forename: K D
authors.initials: KD
authors.lastname: Carnes
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.
authors.forename: I
authors.initials: I
authors.lastname: Ben-Itzhak
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.
authors.forename: C L
authors.initials: CL
authors.lastname: Cocke
authors.affiliation: Department of Chemistry, University of Liege , B-4000 Liege, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Remacle
authors.affiliation: J. R. Macdonald Laboratory, Physics Department, Kansas State University , Manhattan, Kansas 66506, United States.|Department of Physics, Ludwig-Maximilians-Universität Munich , D-85748 Garching, Germany.
authors.forename: M F
authors.initials: MF
authors.lastname: Kling