Surface structure of water from soft X-ray second harmonic generation
The microscopic structure of water's surface is crucial to many natural and industrial processes, but studying its hydrogen bond (H-bond) network directly remains challenging due to the required interfacial sensitivity of experimental techniques. By leveraging advances in flat liquid sheet microjets and terawatt-scale attosecond soft X-ray pulses from the LCLS X-ray free electron laser, we employed soft X-ray second harmonic generation (SXSHG) spectroscopy to examine the liquid water/vapor interface. SXSHG combines the elemental selectivity of X-ray spectroscopies with the surface selectivity of SHG and gives access to the electronic structure of interfacial species. Here, we show the SXSHG spectrum differs from bulk water's X-ray absorption, with its peak shifted several eV, indicating a vastly different electronic environment at the interface as compared to the bulk. First-principles electronic structure calculations show the signal is highly sensitive to H-bond interactions, such as water molecules accepting a single H-bond, which are surface abundant.
Authors
- Walter S. Drisdell (ORCID: https://orcid.org/0000-0002-8693-4562)
- Bailey R. Nebgen (ORCID: https://orcid.org/0000-0003-1006-7092)
- Agostino Marinelli (ORCID: https://orcid.org/0000-0002-7248-4652)
- David Cesar (ORCID: https://orcid.org/0000-0003-3669-1854)
- Douglas Garratt (ORCID: https://orcid.org/0000-0002-8637-9984)
- Joseph Duris (ORCID: https://orcid.org/0000-0002-9930-1166)
- Christina Y. Hampton (ORCID: https://orcid.org/0009-0005-3939-2616)
- Nicholas Sudar (ORCID: https://orcid.org/0000-0003-1373-0654)
- Michael Zuerch (ORCID: https://orcid.org/0000-0001-5151-2119)
- Shane W. Devlin (ORCID: https://orcid.org/0000-0003-3189-5073)
- Tod A. Pascal (ORCID: https://orcid.org/0000-0003-2096-1143)
- Alexandria Do (ORCID: https://orcid.org/0000-0002-9124-6502)
- David J. Hoffman (ORCID: https://orcid.org/0000-0001-8518-7676)
- Georgi L. Dakovski (ORCID: https://orcid.org/0000-0003-1563-1190)
- Daniel Schacher (ORCID: https://orcid.org/0000-0002-4095-6635)
- Erika J. Riffe (ORCID: https://orcid.org/0000-0002-7369-562X)
- Richard J. Saykally (ORCID: https://orcid.org/0000-0001-8942-3656)
- Sasawat Jamnuch (ORCID: https://orcid.org/0000-0002-5130-2127)
- J. D. Koralek (ORCID: https://orcid.org/0000-0001-8289-0497)
- Jacob A. Spies (ORCID: https://orcid.org/0000-0002-0148-4823)
- Kristjan Kunnus (ORCID: https://orcid.org/0000-0002-9777-2685)
- Keith V. Lawler (ORCID: https://orcid.org/0000-0003-1087-5815)
- Franky Bernal (ORCID: https://orcid.org/0000-0001-6653-6367)
- Craig P. Schwartz (ORCID: https://orcid.org/0000-0002-4149-2684)
Institutions
- National Institute of Standards and Technology (US)
- University of Nevada, Las Vegas (US)
- Lawrence Berkeley National Laboratory (US)
- SLAC National Accelerator Laboratory (US)
- University of California San Diego (US)
- Theiss Research (US)
- Material Measurement Laboratory (US)
- University of California, Berkeley (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-11-26
- DOI
- https://doi.org/10.1038/s41467-025-65514-4
- Citations
- 1
- Primary Topic
- Advanced X-ray Imaging Techniques
- Type
- article
- Field-Weighted Citation Impact
- 1.88
Funders
- National Science Foundation
- U.S. Department of Energy
- U.S. Department of Commerce
- National Energy Research Scientific Computing Center
- National Institute of Standards and Technology
- Office of Science
- Office of the President, University of California
- Division of Materials Research
- Office of Advanced Cyberinfrastructure
- Basic Energy Sciences
- Chemical Sciences, Geosciences, and Biosciences Division
- Lawrence Berkeley National Laboratory
- SLAC National Accelerator Laboratory