Jun Wang
Ph.D. Student in Applied Physics, admitted Autumn 2019
All Publications
-
Relativistic effects in molecular photoemission delays
PHYSICAL REVIEW A
2024; 110 (6)
View details for DOI 10.1103/PhysRevA.110.L061101
View details for Web of Science ID 001379640100004
-
Design and performance of a magnetic bottle electron spectrometer for high-energy photoelectron spectroscopy.
The Review of scientific instruments
2024; 95 (12)
Abstract
We describe the design and performance of a magnetic bottle electron spectrometer (MBES) for high-energy electron spectroscopy. Our design features a 2 m long electron drift tube and electrostatic retardation lens, achieving sub-electronvolt (eV) electron kinetic energy resolution for high energy (several hundred eV) electrons with a close to 4π collection solid angle. A segmented anode electron detector enables the simultaneous collection of photoelectron spectra in high resolution and high collection efficiency modes. This versatile instrument is installed at the time-resolved molecular and optical sciences instrument at the Linac Coherent Light Source x-ray free-electron laser (XFEL). In this paper, we demonstrate its high resolution, collection efficiency, and spatial selectivity in measurements where it is coupled to an XFEL source. These combined characteristics are designed to enable high-resolution time-resolved measurements using x-ray photoelectron, absorption, and Auger-Meitner spectroscopy. We also describe the pervasive artifact in MBES time-of-flight spectra that arises from a periodic modulation in electron collection efficiency and present a robust analysis procedure for its removal.
View details for DOI 10.1063/5.0223334
View details for PubMedID 39704606
-
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
-
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
-
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
-
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
-
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
-
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
-
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
-
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