title: Diffractive imaging of a rotational wavepacket in nitrogen molecules with femtosecond megaelectronvolt electron pulses.
abstract: Imaging changes in molecular geometries on their natural femtosecond timescale with sub-Angström spatial precision is one of the critical challenges in the chemical sciences, as the nuclear geometry changes determine the molecular reactivity. For photoexcited molecules, the nuclear dynamics determine the photoenergy conversion path and efficiency. Here we report a gas-phase electron diffraction experiment using megaelectronvolt (MeV) electrons, where we captured the rotational wavepacket dynamics of nonadiabatically laser-aligned nitrogen molecules. We achieved a combination of 100 fs root-mean-squared temporal resolution and sub-Angstrom (0.76 Å) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule. In addition, the diffraction patterns reveal the angular distribution of the molecules, which changes from prolate (aligned) to oblate (anti-aligned) in 300 fs. Our results demonstrate a significant and promising step towards making atomically resolved movies of molecular reactions.
authors.affiliation: Department of Physics and Astronomy, University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.affiliation: PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.|Institute of Physics and Astronomy, Potsdam University, Potsdam 14476, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Guehr
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Theodore
authors.initials: T
authors.lastname: Vecchione
authors.affiliation: Department of Physics and Astronomy, University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA.
authors.forename: Matthew S
authors.identifier: http://orcid.org/0000-0003-3891-6375
authors.initials: MS
authors.lastname: Robinson
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Renkai
authors.initials: R
authors.lastname: Li
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Nick
authors.initials: N
authors.lastname: Hartmann
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Xiaozhe
authors.initials: X
authors.lastname: Shen
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Coffee
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Jeff
authors.initials: J
authors.lastname: Corbett
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Fry
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Gaffney
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Tais
authors.initials: T
authors.lastname: Gorkhover
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Carsten
authors.initials: C
authors.lastname: Hast
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Jobe
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Makasyuk
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Reid
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Robinson
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Vetter
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Fenglin
authors.initials: F
authors.lastname: Wang
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Weathersby
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Charles
authors.identifier: http://orcid.org/0000-0003-2691-5316
authors.initials: C
authors.lastname: Yoneda
authors.affiliation: Department of Physics and Astronomy, University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Centurion
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Xijie
authors.initials: X
authors.lastname: Wang