Diffractive imaging of a rotational wavepacket in nitrogen molecules with femtosecond megaelectronvolt electron pulses

Jie Yang, University of Nebraska - Lincoln
Markus Guehr, Potsdam University, Potsdam
Theodore Vecchione, SLAC National Accelerator Laboratory
Matthew S. Robinson, University of Nebraska-Lincoln
Renkai Li, SLAC National Accelerator Laboratory
Nick Hartmann, SLAC National Accelerator Laboratory
Xiaozhe Shen, SLAC National Accelerator Laboratory
Ryan Coffee, SLAC National Accelerator Laboratory
Jeff Corbett, SLAC National Accelerator Laboratory
Alan Fry, SLAC National Accelerator Laboratory
Kelly Gaffney, SLAC National Accelerator Laboratory
Tais Gorkhover, SLAC National Accelerator Laboratory
Carsten Hast, SLAC National Accelerator Laboratory
Keith Jobe, SLAC National Accelerator Laboratory
Igor Makasyuk, SLAC National Accelerator Laboratory
Alexander Reid, SLAC National Accelerator Laboratory
Joseph Robinson, SLAC National Accelerator Laboratory
Sharon Vetter, SLAC National Accelerator Laboratory
Fenglin Wang, SLAC National Accelerator Laboratory
Stephen Weathersby, SLAC National Accelerator Laboratory
Charles Yoneda, SLAC National Accelerator Laboratory
Martin Centurion, University of Nebraska-Lincoln
Xijie Wang, SLAC National Accelerator Laboratory, Menlo Park, CA

Document Type Article

This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Imaging changes in molecular geometries on their natural femtosecond timescale with sub-Angstro¨m 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 (0.76Å) 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.