Jun Wang
Ph.D. Student in Applied Physics, admitted Autumn 2019
All Publications
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Attosecond delays in X-ray molecular ionization.
Nature
2024; 632 (8026): 762-767
Abstract
The photoelectric effect is not truly instantaneous but exhibits attosecond delays that can reveal complex molecular dynamics1-7. Sub-femtosecond-duration light pulses provide the requisite tools to resolve the dynamics of photoionization8-12. Accordingly, the past decade has produced a large volume of work on photoionization delays following single-photon absorption of an extreme ultraviolet photon. However, the measurement of time-resolved core-level photoionization remained out of reach. The required X-ray photon energies needed for core-level photoionization were not available with attosecond tabletop sources. Here we report measurements of the X-ray photoemission delay of core-level electrons, with unexpectedly large delays, ranging up to 700 as in NO near the oxygen K-shell threshold. These measurements exploit attosecond soft X-ray pulses from a free-electron laser to scan across the entire region near the K-shell threshold. Furthermore, we find that the delay spectrum is richly modulated, suggesting several contributions, including transient trapping of the photoelectron owing to shape resonances, collisions with the Auger-Meitner electron that is emitted in the rapid non-radiative relaxation of the molecule and multi-electron scattering effects. The results demonstrate how X-ray attosecond experiments, supported by comprehensive theoretical modelling, can unravel the complex correlated dynamics of core-level photoionization.
View details for DOI 10.1038/s41586-024-07771-9
View details for PubMedID 39169246
View details for PubMedCentralID 7399650
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Terawatt-scale attosecond X-ray pulses from a cascaded superradiant free-electron laser
NATURE PHOTONICS
2024
View details for DOI 10.1038/s41566-024-01427-w
View details for Web of Science ID 001220935700001
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Experimental demonstration of attosecond pump-probe spectroscopy with an X-ray free-electron laser
NATURE PHOTONICS
2024
View details for DOI 10.1038/s41566-024-01419-w
View details for Web of Science ID 001200371400001
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Time-Resolved X-ray Photoelectron Spectroscopy: Ultrafast Dynamics in CS2 Probed at the S 2p Edge.
The journal of physical chemistry letters
2023: 7126-7133
Abstract
Recent developments in X-ray free-electron lasers have enabled a novel site-selective probe of coupled nuclear and electronic dynamics in photoexcited molecules, time-resolved X-ray photoelectron spectroscopy (TRXPS). We present results from a joint experimental and theoretical TRXPS study of the well-characterized ultraviolet photodissociation of CS2, a prototypical system for understanding non-adiabatic dynamics. These results demonstrate that the sulfur 2p binding energy is sensitive to changes in the nuclear structure following photoexcitation, which ultimately leads to dissociation into CS and S photoproducts. We are able to assign the main X-ray spectroscopic features to the CS and S products via comparison to a first-principles determination of the TRXPS based on ab initio multiple-spawning simulations. Our results demonstrate the use of TRXPS as a local probe of complex ultrafast photodissociation dynamics involving multimodal vibrational coupling, nonradiative transitions between electronic states, and multiple final product channels.
View details for DOI 10.1021/acs.jpclett.3c01447
View details for PubMedID 37534743
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Photon energy-resolved velocity map imaging from spectral domain ghost imaging
NEW JOURNAL OF PHYSICS
2023; 25 (3)
View details for DOI 10.1088/1367-2630/acc201
View details for Web of Science ID 000956244500001
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Controlled melting of a Wigner ion crystal with atomic resolution
PHYSICAL REVIEW A
2020; 102 (6)
View details for DOI 10.1103/PhysRevA.102.063121
View details for Web of Science ID 000602805100007
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Scalable quantum tomography with fidelity estimation
PHYSICAL REVIEW A
2020; 101 (3)
View details for DOI 10.1103/PhysRevA.101.032321
View details for Web of Science ID 000519697000007
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Unsupervised Generative Modeling Using Matrix Product States
PHYSICAL REVIEW X
2018; 8 (3)
View details for DOI 10.1103/PhysRevX.8.031012
View details for Web of Science ID 000438882400001