Femtosecond Electronic and Hydrogen Structural Dynamics in Ammonia Imaged with Ultrafast Electron Diffraction

Authors

Elio G. Champenois, SLAC National Accelerator Laboratory
Nanna H. List, KTH Royal Institute of Technology
Matthew Ware, SLAC National Accelerator Laboratory
Mathew Britton, SLAC National Accelerator Laboratory, Stanford University
Philip H. Bucksbaum, SLAC National Accelerator Laboratory, Stanford University
Xinxin Cheng, SLAC National Accelerator Laboratory
Martin Centurion, University of Nebraska - LincolnFollow
James P. Cryan, SLAC National Accelerator Laboratory
Ruaridh Forbes, SLAC National Accelerator Laboratory
Ian Gabalski, SLAC National Accelerator Laboratory, Stanford University
Kareem Hegazy, SLAC National Accelerator Laboratory, Stanford University
Matthias C. Hoffmann, SLAC National Accelerator Laboratory
Andrew J. Howard, SLAC National Accelerator Laboratory, Stanford University
Fuhao Ji, SLAC National Accelerator Laboratory
Ming-Fu Lin, SLAC National Accelerator Laboratory
J. Pedro F. Nunes, University of Nebraska-Lincoln
Xiaozhe Shen, SLAC National Accelerator Laboratory
Jie Yang, SLAC National Accelerator Laboratory, Tsinghua University
Xijie Wang, SLAC National Accelerator Laboratory
Todd J. Martinez, SLAC National Accelerator Laboratory, Stanford University
Thomas J. A. Wolf, SLAC National Accelerator Laboratory

Document Type

Article

Date of this Version

2023

Citation

PHYSICAL REVIEW LETTERS 131, 143001 (2023). DOI: 10.1103/PhysRevLett.131.143001

Comments

Used by permission.

Abstract

Directly imaging structural dynamics involving hydrogen atoms by ultrafast diffraction methods is complicated by their low scattering cross sections. Here we demonstrate that megaelectronvolt ultrafast electron diffraction is sufficiently sensitive to follow hydrogen dynamics in isolated molecules. In a study of the photodissociation of gas phase ammonia, we simultaneously observe signatures of the nuclear and corresponding electronic structure changes resulting from the dissociation dynamics in the time-dependent diffraction. Both assignments are confirmed by ab initio simulations of the photochemical dynamics and the resulting diffraction observable. While the temporal resolution of the experiment is insufficient to resolve the dissociation in time, our results represent an important step towards the observation of proton dynamics in real space and time.