Laser-induced electron diffraction of the ultrafast umbrella motion in\n ammonia

2020/12/30 by Blanca Belsa, Belsa, Blanca, Kasra Amini +25 · 1 citation
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Laser-Matter Interactions and Applications #Mass Spectrometry Techniques and Applications

paper · pdf · doi:10.48550/arxiv.2012.15374

openalex publication_date 2020/12/30 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28

Abstract

Visualizing molecular transformations in real-time requires a structural\nretrieval method with AAngstr "om spatial and femtosecond temporal atomic\nresolution. Imaging of hydrogen-containing molecules additionally requires an\nimaging method that is sensitive to the atomic positions of hydrogen nuclei,\nwith most methods possessing relatively low sensitivity to hydrogen scattering.\nLaser-induced electron diffraction (LIED) is a table top technique that can\nimage ultrafast structural changes of gas-phase polyatomic molecules with\nsub- AAngstr "om and femtosecond spatiotemporal resolution together with\nrelatively high sensitivity to hydrogen scattering. Here, we image the umbrella\nmotion of an isolated ammonia molecule (NH₃) following its strong field\nionization. Upon ionization of a neutral ammonia molecule, the ammonia cation\n(NH₃⁺) undergoes an ultrafast geometrical transformation from a pyramidal\n(\Φ_HNH = 107 ^\∘) to planar (\Φ_HNH=120^\∘) structure in\napproximately 8 femtoseconds. Using LIED, we retrieve a near-planar\n(\Φ_HNH=117 \± 5^\∘) field-dressed NH₃⁺ molecular structure\n7.8-9.8 femtoseconds after ionization. Our measured field-dressed NH₃⁺\nstructure is in excellent agreement with our calculated equilibrium field\ndressed structure using quantum chemical ab initio calculations.\n

Cited by

• Orbital distortion and parabolic channel effects transform minima in molecular ionization probabilities into maxima

Related

• Femtosecond electronic and hydrogen structural dynamics in ammonia imaged with ultrafast electron diffraction
• Probing valence electron and hydrogen dynamics using charge-pair imaging with ultrafast electron diffraction
• Imaging valence electron rearrangement in a chemical reaction using hard X-ray scattering
• Perspective: Ultrafast Imaging of Molecular Dynamics Using Ultrafast Low-Frequency Lasers, X-ray Free Electron Laser and Electron Pulses
• Machine learning for laser-induced electron diffraction imaging of molecular structures