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Published on: June 27, 2014
Time-Resolved X-ray Photoelectron Spectroscopy: Probing Bond Order Rearrangements during Ultrafast Excited-State
Victor M Freixas1, Axel Gomez2, Yonghao Gu1
1Department of Chemistry, Department of Physics and Astronomy, University of California, Irvine, California 92697, United States.
Journal of Chemical Theory and Computation
|July 23, 2026
Summary
Time-resolved X-ray photoelectron spectroscopy (tr-XPS) tracks excited-state intramolecular proton transfer (ESIPT) dynamics. This method reveals site-specific bond rearrangements, offering insights into chemical reactions.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Spectroscopy
Background:
- Excited-state intramolecular proton transfer (ESIPT) is a fundamental process involving bond order changes.
- Studying ESIPT dynamics requires advanced spectroscopic techniques with site-specific resolution.
Purpose of the Study:
- To investigate the dynamics of ESIPT in 10-hydroxybenzo[h]quinoline (HBQ) and its deuterated analog (DBQ).
- To demonstrate the capability of time-resolved X-ray photoelectron spectroscopy (tr-XPS) as a site-specific probe for ESIPT.
Main Methods:
- Linear-response time-dependent density functional theory (TDDFT) calculations.
- Ab initio molecular dynamics simulations.
- Neural network potentials incorporating nuclear quantum effects.
- Time-resolved X-ray photoelectron spectroscopy (tr-XPS) with tunable photoionization probe energy.
Main Results:
- tr-XPS signals show strong dependence on ESIPT, with changes in photoelectron yield and binding energy.
- Site-specific ionization of oxygen or nitrogen atoms provides distinct spectral information.
- Isotope effects (HBQ vs. DBQ) reveal differences in ESIPT timescales and oscillatory spectral features linked to bond rearrangements.
Conclusions:
- tr-XPS is a powerful technique for site-specifically probing ESIPT dynamics.
- The method is sensitive to local charge redistribution and bond-order rearrangements during ESIPT.
- This work highlights the potential of tr-XPS for future experimental studies of chemical dynamics.
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