Photocontrol of Growth Rate of Thin Polymer Films Formed by Electron Bombardment

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Abstract
This paper reports on an exploratory study concerned with the formation of thin polymer films on metal film substrates bombarded by slow electrons. The essential results of the investigation are: Cracking, polymerization, and crosslinking of organic molecules adsorbed on surfaces by electron bombardment can be achieved with electron energies as low as 6 eV. The formation rate of thin polymer films in the low electron region is voltage‐dependent. Polymer films formed from organic molecules inherently present in a high vacuum system show electrical photoresponse in the visible and near‐infrared region of the spectrum. By utilizing this photoresponse and the voltage dependence of the film growth rate, polymer film configurations can be grown which correspond to light patterns projected onto them. All experiments were conducted in an electron mirror microscope which proved to ideally suited for this type of study. Such a microscope is a very sensitive tool for the detection and observation of extremely thin insulating films. It permits formation of thin polymer films in an easy fashion and it serves equally well as a convenient instrument for immediate detection and study of such films during growth. The transition from growing polymer films to observing them can be accomplished simply by switching the bias potential on the polymer film's conductive substrate. In one example, illustrated by an electron mirror micrograph, the experimental procedures are described in detail.