X-Ray and Optical Properties of Barium-Copper-Stearate Films

Abstract

Barium-copper-stearate films, built by the successive deposition of layers one molecule thick, were used as diffraction crystals to obtain x-ray spectra. The measurements show that for these films the x-ray spacing has a constant value of approximately 50.47 A for films with the same composition, with thicknesses varying from 301 to 3000 layers, but varies with the percent of copper in the film; thin films produce as good spectra as do thick ones; the reflecting planes are regular and definite; the spacing is the same whether the molecules in adjacent layers are oriented in the same or in opposite directions; and the unit decrement of the index of refraction is 5.1×${10}^{-6\mathrm{}}$. From the total thickness of a film, as measured by a Michelson interferometer, the spacing of the molecular layers was found to be 24.23 A. For the films in which the molecules in adjacent layers were oriented in opposite directions it was expected that the grating space would be twice the layer spacing, or 48.46 A. The marked difference between this value and the x-ray spacing of 50.47 A indicates that the x-ray spacing is not determined by the method of building the film.