Contact Charge Transfer between Nominally Identical Materials

Abstract

AbstractDifferences in concentrations of excited electrons arising from geometry‐dependent differences in de‐excitation paths lead to differences in Fermi energies, which enable contact charge transfer between otherwise identical solids of different size. This model is used with a quasi‐equilibrium description of the Fermi energy to estimate a lower bound of the magnitude of charging of pairs of like particles and the charge distribution in groups of interacting like particles. The predictions agree with observed charge transfer directions between large and small particles and with the broad particle size range over which charging is observed. Estimates of charging are compared to available measurements, the breakdown limits of air, and the relative strengths of interparticle electrostatic and gravitational forces. The influence of particle size distribution on the charge distribution in groups of particles is examined.