Probing aqueous interfaces with spin defects

Area of Science:

• Physical Chemistry
• Materials Science
• Quantum Sensing

Background:

• Aqueous interfaces are crucial in many scientific fields, but their microscopic properties are challenging to measure.
• Advanced spectroscopic techniques have improved, yet direct characterization of interfacial water dynamics remains difficult.

Purpose of the Study:

• To explore noise spectroscopy for characterizing aqueous interfacial properties.
• To investigate the impact of interfacial water and ions on quantum sensors hosted in 2D materials.

Main Methods:

• Combined molecular dynamics simulations of water on a 2D substrate with calculations of spin defect dynamics.
• Analyzed the influence of interfacial water and ions on the decoherence time of a model quantum sensor (spin defect).

Main Results:

• Quantum sensor coherence time (Hahn echo) is sensitive to water's motional narrowing and hydrogen bonding.
• Interfacial water dynamics and ion presence significantly affect sensor decoherence.
• Results show sensitivity to temperature, water-surface interaction strength, and ion type (monovalent/divalent).

Conclusions:

• Noise spectroscopy, using near-surface quantum sensors, provides a powerful tool to probe aqueous interface properties.
• This approach offers broad applicability for understanding interfacial phenomena across various scientific disciplines.