The technique of the total reflection of x rays has been applied to the study of thin films of Cu, Ni, Ge, and Se vacuum-deposited onto polished glass substrates. Starting with fresh films, ``smooth'' enough to exhibit pronounced x-ray interference fringes in the region just beyond the critical angle, the effects of vacuum anneal and oxidation were studied. Changes in the reflection curves are interpreted in terms of possible structural changes in the films. Reflection from layers of particles of carbon or polystyrene latex deposited onto ``smooth'' substrates was also studied for comparison.

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Density measurements have been made on vacuum-deposited copper films in the thickness ranges 50 to 150 A and 500 to 1000 A. To obtain the density, an analysis was made of the relation between the reflection coefficient and the glancing angle of incidence for 1.54 A x-rays. For films in the range 500 to 100 A, this analysis was augmented by a chemical determination of the average mass per unit area. Although there is evidence of nonuniform density with depth in the film, especially for the very thin films, the average density of a film thicker than about 300 A was found within the limits of the experimental accuracy to be equal to the bulk density. This conclusion is in disagreement with some previously published work; the discrepancy appears to lie in differences between the x-ray method of measuring film thickness and the conventional optical interference method.

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Absolute photoelectric yields of Ni, Cu, Pt, Au, W, Mo, Ag, and Pd are presented for the spectral region from 1400 to 473 A. Measurements were obtained for commercially pure polycrystalline surfaces which were treated in various ways including heat treatment in vacuo and in various gas atmospheres at reduced pressures. Surfaces, heat treated in vacuo, gave reproducible yields ranging from 10−3 electrons per photon at 1400 A to 10−1 electrons per photon at 500 A. Although untreated samples exhibited a maximum in the region studied, this maximum disappeared after heat treatment resulting in most cases in a broad plateau extending from 1000 A to 500 A. At wavelengths longer than 1000 A a decrease in yield was observed. Representative experiments with a Ni cathode, heat treated in vacuo then exposed to O2 at reduced pressures, indicated that the maxima for untreated surfaces were caused by adsorbed gases and metallic oxide formation. The absolute error in the values of the photoyields was estimated to be within ±15%.

Photolytic darkening and electron range were investigated for a series of silver chloride crystals cut from a single boule which was grown in vacuum by the Bridgman technique. The effect of annealing atmosphere on both the initial darkening rate and electron range is discussed. Darkening produced by absorption of light in the tail of the fundamental band is shown to have a volume and a surface component. The volume darkening produced in a vacuum-annealed crystal is capable of absorbing but not scattering light. The darkened crystal can be bleached selectively with high efficiency by exposure to light near the peak of the induced absorption band. Difficulty is found with interpreting the results entirely in terms of a classical theory for light absorption by colloidal particles suspended in a dielectric medium. Crystals annealed in air darken quite differently then vacuum-annealed samples and crystals heated in chlorine show little sensitivity to light. Somewhat smaller but regular differences in low-temperature electron range were found for the various crystals heat treated in different annealing atmospheres.

Recently it was found that x-ray interference phenomena could be observed in the nonspecularly scattered radiation from thin metallic films. In the present investigation, the interference phenomena which manifested themselves in both the specularly and the nonspecularly scattered x rays from multilayer barium stearate films were examined. Several new features were observed in the scattered radiation, and analysis of the interference patterns yielded values of the total multilayer film thickness and the double-layer spacing. The value obtained for the double-layer spacing is 50.3 A and this value is consistent with values found by other investigators.

The phenomenon of x-ray interference upon reflection from thin films is well known. Superposed on this interference a second interference phenomenon has been found which manifests itself as structure in the scattered radiation accompanying the specularly reflected x-ray beam. This new phenomenon is attributed to an interference between the components of scattered radiation originating at the two surfaces of the film. This interference structure in the scattered radiation has been analyzed and used to determine the thickness of vacuum deposited copper films ranging in thickness from 250 to 1000 A. The results were consistent with those obtained by previously described techniques.