Surface roughness induced electric field enhancement and triboluminescence

TL;DR

This paper explores how surface roughness and ion/electron diffusion during solid separation or fracture lead to electric field enhancement and triboluminescence, explaining high-energy photon emission.

Contribution

It introduces a model linking surface roughness and charge concentration to electric field enhancement and photon emission during solid separation.

Findings

Surface roughness concentrates charge at asperity tips.

Electric field enhancement facilitates high-energy photon emission.

Discharging behavior depends on surface diffusion speed.

Abstract

The separation of solids in adhesive contact, or the fracture of solid bodies, often results in the emission of high energy photons, e.g., visible light and X-rays. This is believed to be related to charge separation. We propose that the emission of high energy photons involves surface roughness and surface diffusion of ions or electrons, resulting in the concentration of charge at the tips of high asperities, and to electric field enhancement, which facilitate the discharging process which result in the high energy photons. If the surface diffusion is too fast, or the separation of the solid surfaces too slow, discharging start at small interfacial separation resulting in low energy photons.