Abstract

Visualizing molecular transformations in real-time requires a structural retrieval method with Ångström spatial and femtosecond temporal atomic resolution. Imaging of hydrogen-containing molecules additionally requires an imaging method sensitive to the atomic positions of hydrogen nuclei, with most methods possessing relatively low sensitivity to hydrogen scattering. Laser-induced electron diffraction (LIED) is a table-top technique that can image ultrafast structural changes of gas-phase polyatomic molecules with sub-Ångström and femtosecond spatiotemporal resolution together with relatively high sensitivity to hydrogen scattering. Here, we image the umbrella motion of an isolated ammonia molecule (NH3) following its strong-field ionization. Upon ionization of a neutral ammonia molecule, the ammonia cation (NH3+) undergoes an ultrafast geometrical transformation from a pyramidal (φHNH = 107 °) to planar (φHNH = 120 °) structure in approximately 8 femtoseconds. Using LIED, we retrieve a near-planar (φHNH = 117 ± 5 °) field-dressed NH3+ molecular structure 7.8 - 9.8 femtoseconds after ionization. Our measured field-dressed NH3+ structure is in excellent agreement with our calculated equilibrium field-dressed structure using quantum chemical ab initio calculations.

Department(s)

Physics

International Standard Serial Number (ISSN)

2329-7778

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2021 The Authors, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.

Publication Date

01 Jan 2021

Included in

Physics Commons

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