An Electron Microscope Study of Gold Smoke Deposits

Abstract

Gold smoke deposits have been examined at high resolution with the electron microscope, and the size and distribution of the unit particles determined. The smokes were produced by evaporating gold from a hot tungsten filament in a partial atmosphere of nitrogen, and the samples were collected on thin collodion films. It was found that the size of the unit colloidal gold particles varied with the pressure of the atmosphere and the rate of evaporation. The manner of aggregation of the particles was found to be independent of the nitrogen atmosphere pressure and rate of evaporation over a relatively wide range. The aggregations, however, changed markedly when a small amount of oxygen was present during the evaporation. Measurements in the visible and infra-red regions of the spectrum were correlated with the electron microscope investigations, and it was found that the optical properties of the deposits depend strikingly upon the manner in which the smoke particles aggregate and how the aggregates are distributed.