Surface structure of water from soft X-ray second harmonic generation.

ABSTRACT: 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

SUBMITTER: Hoffman DJ 

PROVIDER: S-EPMC12658203 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature