The production and properties of thin films of lead monoxide

An account is given of the conditions necessary to produce stable, highly reflecting films of lead monoxide with low absorption. At a substrate temperature of 200° C and in an atmosphere of oxygen at a pressure of 0.35 mtorr, a film of refractive index n d = 2.74 was obtained with extremely low absorption. The oxygen atmosphere was produced in situ by heating manganese dioxide with the evaporant. In combination with magnesium fluoride a 13 layer stack was prepared with a reflectivity of 99.7%, falling to 99.1% after exposure in the laboratory for 2 months.