Contact Electrification: Observations of Self-Charging and a Novel Probing Technique

We present observations of charge exchange between identical single-crystal insulators with charge densities reaching magnitudes comparable to those observed between dissimilar materials. Any complete theory of contact electrification must be held accountable to these observations, leading to significant constraints on possible underlying mechanisms of charge transfer between insulators. This self-charging behavior does not appear random when repeated contacts are made, suggesting the possibility of a nucleation-type event developing from seed charges. To investigate this theory we have designed an in-situ probing technique that is non-invasive, allowing for observations of the detailed evolution of the charge distribution on insulating surfaces.