Reflectivity curves have been calculated for mosaic crystals in the case of normal-incidence Bragg diffraction with soft X-rays. The enormously broadened angular width of a reflection when the angle of incidence to the reflecting Bragg plane approaches 90° allows a single crystal with a mosaic spread as much as a few degrees to give a reflectivity profile very similar to that of a perfect crystal, when the incident photon energy is scanned. The insensitivity of the diffraction process to crystal mosaicity can be exploited in standing-wave experiments aimed at the determination of substrate-overlayer interface structures.

No abstract

No abstract

No abstract

A brief review of established methods shows that only with the Berthelot technique is it possible to see a finite volume of liquid in sustained mechanical tension. A short discussion of the practice and theory reveals two uncertainties with the conventional technique : that of the determination of a true filling temperature, and the influence of compliance by the glass on the tension developed. A description is then given of a modified apparatus with which these difficulties do not arise. The tube is formed into a coil which deflects sufficiently to indicate internal pressure or tension, and by monitoring these deflections with a distance meter a record of pressure/ tension against temperature can be made. The course of a typical run is shown from which the excess pressure, filling temperature and limiting tension may all be estimated with much greater precision than befoie. The orders of magnitude of the results obtained are indicated, and a possible influence of non-uniform gaseous supersaturation is suggested.