Quantitative analysis of aligned-molecule photoelectron angular distributions

Woodhouse, Joanne L.; Thompson, James O. F.; Benda, Jakub; Chapman, Richard T.; Hockett, Paul; Makhija, Varun; Mašín, Zdeněk; Reid, Katharine L.; Springate, Emma; Wyatt, Adam S.; Zhang, Yu; Minns, Russell S.

Abstract

Molecular frame photoelectron angular distributions (MFPADs) provide the full available detail of the photoionization process. Careful analysis of the evolving photoelectron angular distribution during the coherent rotation of a nonadiabatically aligned sample of molecules allows the detail which is smoothed out by orientational averaging in the laboratory frame to be resolved. Here we exploit a high flux monochromated HHG lightsource to provide single-photon photoelectron angular distributions of field-free aligned molecules. Our measurements are sensitive to alignment frame variations in even 𝛽𝑛 parameters up to 𝑛=6 in the PADs of the first four ionization channels of OCS, allowing for rigorous benchmarking of the cutting edge theoretical methods used for simulation of MFPADs. We demonstrate that experimentally derived molecular alignment distributions may be combined with theoretical MFPADs to generate theoretical alignment-frame PADs which provide a quantitative comparison to the experimental 𝛽𝑛 parameters. The experimental data and ePSproc simulated PADs show quantitative agreement and sensitivity to picometer-scale changes in the molecular geometry. This combined methodology therefore provides a versatile way of studying geometry-sensitive continuum structural features for nondissociative ionization processes which may not be studied in the recoil frame. These measurements therefore provide a strict test of the theoretical descriptions and will stand as benchmark measurements for future comparisons to higher-level theory.

Citation

Woodhouse, J. L., Thompson, J. O. F., Benda, J., Chapman, R. T., Hockett, P., Makhija, V., Mašín, Z., Reid, K. L., Springate, E., Wyatt, A. S., Zhang, Y., & Minns, R. S. (2025). Quantitative analysis of aligned-molecule photoelectron angular distributions. Physical Review A, 111(1), Article 012815. https://doi.org/10.1103/physreva.111.012815

• Journal Article Type: Article
• Acceptance Date: Dec 19, 2024
• Online Publication Date: Jan 23, 2025
• Publication Date: Jan 23, 2025
• Deposit Date: Feb 6, 2025
• Publicly Available Date: Feb 6, 2025
• Journal: Physical Review A
• Print ISSN: 2469-9926
• Electronic ISSN: 2469-9934
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 111
• Issue: 1
• Article Number: 012815
• DOI: https://doi.org/10.1103/physreva.111.012815
• Public URL: https://nottingham-repository.worktribe.com/output/44538626
• Publisher URL: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.012815