Abstract
Various anodizing conditions and follow-up processes have been investigated to obtain films that have fine pores and are transparent in the infrared region One of the most successful minimizations of pore diameter was achieved by a combination of reducing the voltage in the process of forming a film in oxalic acid, and sealing the film with humidity. This film has fine pores at the section near the barrier layer, pore diameter was estimated at 1nm by measuring the dependence of gas permeability on the molecular diameter of different gases The pores are so fine that the separation factor for He and Xe is twice as large as the value predicted by Knudsen's law We have also developed films that have fine pores at the center, as well as films with fine pores at the surfaces, both have pore shapes that are symmetrical along the axis. Some of these films are capable of incorporating molecules into the film Films formed in chromic acid electrolyte are transparent at wavelengths of 1∼9μm
