Electrical discharge in a nanometer-sized air/water gap observed by atomic force microscopy

Area of Science:

• Physics
• Materials Science
• Chemistry

Background:

• Electrical discharges in confined spaces are poorly understood.
• Nanoscale phenomena present unique challenges for investigation.

Purpose of the Study:

• To develop and demonstrate a method for initiating and studying electrical discharges in nanometer-sized gaps.
• To investigate the factors influencing discharge probability and the resulting physical phenomena.

Main Methods:

• Utilized a standard atomic force microscopy (AFM) setup to create a discharge gap of <= 5 nm between an AFM probe and a substrate.
• Combined experimental AFM observations with computational simulations including boundary element method (BEM), finite element method (FEM), and method of characteristics (MOC).

Main Results:

• Observed highly localized stochastic nanoexplosions.
• Discharge probability was found to be dependent on electric field, material-specific surface reactions, and humidity.
• Identified the generation and propagation of transient shock waves within the nanoscale discharge.
• Demonstrated that shock wave propagation aids in the radial expansion of ionized particles, forming microscale patterns.

Conclusions:

• Provided initial understanding of nanoscale electrical discharges and associated phenomena.
• Findings suggest potential applications in nano/microstructuring, microelectronics, and plasma-assisted deposition techniques.