Measuring Extended Water Interfacial Structures. Water Nanoclusters (∼50 nm) Involved by Ice-like II Walls (∼10 nm).

Area of Science:

• Physical Chemistry
• Materials Science
• Surface Science

Background:

• Interfacial water layers significantly influence surface properties and chemical reactions.
• Understanding the dielectric properties of interfacial water is crucial for various applications, including nanotechnology and biosensing.

Purpose of the Study:

• To investigate the structural differences and dielectric properties of water layers on hydrophobic and hydrophilic substrates.
• To elucidate the formation of ice-like structures and their impact on the dielectric permittivity of interfacial water.

Main Methods:

• Atomic Force Microscopy (AFM) was employed to probe the spatially variable dielectric constant profiles.
• Analysis of nanosized water clusters and their structural arrangements at air/water interfaces.

Main Results:

• Interfacial water layers on both hydrophobic and hydrophilic surfaces display low dielectric permittivity.
• Nanosized water clusters (approximately 50 nm) exhibit an ice-like structure, forming walls with a dielectric constant of ~7.6.
• These walls, composed of an ice-like II arrangement, surround regions with a dielectric constant of ~3.6, forming wired water structures.

Conclusions:

• Two distinct nonequilibrium arrangements of interfacial water contribute to the observed spatially variable dielectric constant.
• The formation of ice-like structures is a key factor in the reduced dielectric permittivity of interfacial water layers.