Bipolar Steady State Charge Fraction of Ultrafine Aerosols

Abstract

Bipolar steady state charge fractions of monodisperse aerosols under 150 Å in diameter have been measured. The steady state charge fractions of particles under 150 Å were observed to be an order of magnitude greater than that predicted by Boltzmann's law, and the negative charge fraction was nearly twice as large as the positive charge fraction. For example, 5% of 100-Å particles were observed to be negatively charged, while 3% were positively charged; Boltzman's law predicts approximately 0.3% of 100-Å particles to be charged. Further, particles under 150 Å were observed to be only singly charged.