Prof. Ying Jiang’s group from Peking University Developed A Quantum Microscope Technique for Solid-Liquid Interfacial Detection

Recently, Prof. Ying Jiang from the International Center for Quantum Materials and Interdisciplinary Institute of Light-Element Quantum Materials at Peking University, in collaboration with Prof. Sheng Meng from the Institute of Physics, Chinese Academy of Science, has led to the development of a novel quantum microscope technique. By combining scanning probe microscopy (SPM) with quantum sensing, they developed a method that is sensitive to solid-liquid interfaces. This method enabled the investigation of the critical steps of interfacial water dissociation at the nanoscale, including electron transfer, bond breaking, and water/hydrogen diffusion.

This work, titled “Probing interfacial water dissociation at the nanoscale with a quantum sensor”, was published in the Physical Review Letters on November 10^th and selected by the Editors’ suggestion. Meanwhile, the American Physical Society's journal Physics has published a Viewpoint titled "A Quantum Microscope Reveals Water Breaking Apart", which highlighted this work as a scientific breakthrough born from the combination of two independent methods.

Figure 1: The scheme of a quantum microscope (NV-SPM) by combining diamond-based quantum sensing and SPM, which can trigger water dissociation at the solid-liquid interface with nanometer precision and observe its elementary steps. Figure 1 was reprinted from the "Viewpoint" article in Physics, published by the American Physical Society. 

How to resolve interfacial phenomena from a microscopic view is one of 125 pivotal scientific questions posed by Science in 2021. Among these, high-resolution probing of the solid-liquid interface remains a core challenge. Existing techniques, such as vibrational spectroscopy (e.g., infrared and Raman spectroscopy), primarily rely on the analysis of molecules’ "chemical fingerprints". However, their limitations lie not only in the difficulty of directly translating into precise structures of molecules but also in their high insensitivity to unpaired electrons. Therefore, developing new methods that directly target the fundamental building blocks of matter (e.g., electrons and nuclei) at the nanoscale holds the potential to overcome existing bottlenecks and pioneer a new pathway for resolving material structures.

Ying Jiang and his group have long been dedicated to the development of advanced SPM technologies. Recently, by integrating quantum sensing based on the nitrogen-vacancy (NV) center with qPlus-SPM, they successfully constructed a scanning quantum sensing microscope (NV-SPM, Rev. Sci. Instrum. 95, 053707 (2024)). This achievement enabled the first NV-based nanoscale electric field imaging and pushed shallow NV’s sensitivity close to single protons (Nat. Commun. 12, 2457 (2021); Nat. Phys. 18, 1317 (2022)).

Here, Jiang et. al. developed a novel method sensitive to solid-liquid interfaces by combining NV-based nanoscale magnetic resonance measurements with high-precision SPM tip manipulation (Fig. 1). They utilized the tip to locally inject electrons, inducing interfacial water dissociation on a diamond surface. Then, they employed shallow NVs to detect electron/nuclear spins at the nanoscale, systematically probing elementary steps including electron transfer, chemical bond breaking, and hydrogen diffusion.

Jiang et. al. applied the SPM tip to locally inject electrons into the interfacial water, and measured the resulting hydrated electrons (eˉ_(aq)) by NV-based double-electron-electron resonance (DEER). A hyperfine interaction around 28 MHz of eˉ_(aq) was found, which agrees well with density functional theory (DFT) calculations by Meng’s Group (Fig. 2a and b), indicating that a specific hydrated configuration of eˉ_(aq) was formed at the hydrophilic diamond surface. Using NV-based nuclear magnetic resonance correlation spectroscopy, the authors observed that eˉ_(aq) can further induce water dissociation, where the reaction product hydroxides (OHˉ) diffuse ~2.3 times faster than water molecules (H₂O). The diffusion coefficients of H₂O and OHˉ at the interface are about three orders of magnitude smaller than those in the bulk phase, but their ratio almost remained the same (Fig. 2d).

The technique developed here tackles a central challenge in probing solid-liquid interfaces, paving the way for unprecedented insights into their microstructure and dynamics and promising a paradigm shift in diverse research fields.

Figure 2 (a): DEER of a shallow NV center with (red curve) and without (blue curve) eˉ_(aq). With eˉ_(aq), the two shoulders appear at f₁=1.513 GHz and f₂=1.574 GHz, resulting from the hyperfine interaction of eˉ_(aq). (b): Distribution of the calculated hyperfine parameter (|Azz|) of eˉ_(aq), showing a maximum of around 28 MHz. Inset: one of the simulated representative structures of eˉ_(aq). (c): Correlation data using XY8-4 based on a single NV under different tip biases. The oscillation shows a decayed envelope caused by the diffusion of protons in H₂O and OHˉ. (d): The ratio of proton diffusion coefficients in interfacial H₂O and OHˉ. Figure 2 was adapted from the paper in Physical Review Letters, published by the American Physical Society. 

Ying Jiang, Ke Bian, and Sheng Meng are the corresponding authors. Wentian Zheng, Ke Bian, and Jiyu Xu are the co-first authors. This work was financially supported by the National Natural Science Foundation of China, the Ministry of Science and Technology, New Cornerstone Science Foundation, Beijing Outstanding Young Scientist Program, and the Beijing Municipal Science & Technology Commission. 

The paper in Physical Review Letters, published by the American Physical Society:

Wentian Zheng; Ke Bian; Jiyu Xu; Xiakun Chen; Shichen Zhang; Rainer Stöhr; Andrej Denisenko; Jörg Wrachtrup; Sheng Meng; Ying Jiang; Probing interfacial water dissociation at the nanoscale with a quantum sensor, Physical Review Letters, 135, 208001 (2025). (https://journals.aps.org/prl/abstract/10.1103/gpcy-lnc2)

The Viewpoint article in Physics, published by the American Physical Society：

Jan Balajka, A Quantum Microscope Reveals Water Breaking Apart (https://physics.aps.org/articles/v18/180)