Motion Picture Studies of Electron Bombardment of Colloidal Crystals

Phenomena not seen or recorded by orthodox methods are observed on the large number of micrographs which are taken during a motion picture experiment, and reaction times as short as 0.03 sec. can be calculated. The technique is useful for investigating solid-liquid-solid changes both by direct observation and by recording Bragg reflections. In most cases a preliminary effect of electrons upon crystals is to drive off water. In the case of sodium chloride crystals a residual envelope is left. Inside this, small particles, both solid and liquid, are observed to move rapidly due, it is believed, to a combination of Brownian movement and convection. These gradually evaporate and diffuse through the wall. The possibility is discussed that the residual envelope is formed by contamination. Examples are also taken from bombarded, colloidal crystals of tungsten oxide.