X-ray intensity measurements on large crystals by energy-dispersive diffractometry. IV. Determination of anomalous scattering factors near the absorption edges of GaAs by the one-intensity-ratio method
The internal strain tensor of crystals having the diamond structure has a single independent component {\bar A}. A value {\bar A} = −0.18±0.01 for silicon has been found by observing the 006 forbidden reflection whilst applying a stress along the [1{\bar 1}0] axis. An energy-dispersive method was used so that advantage could be taken of the simultaneous presence of strong reflections (004 and 008) to align the sample with precision and to normalize the intensity measurements. In the course of investigation it was found that the strong reflections increased in intensity as a function of stress, suggesting that the crystal was undergoing a reversible change from the ideally perfect to the ideally imperfect state.
Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.
SummaryThe importance and difficulties of determining the height of hard X-ray sources in the solar atmosphere, in order to distinguish source models, have been discussed by Brown and McClymont (1974) and also in this Symposium (Brown, 1975; Datlowe, 1975). Theoretical predictions of this height, h, range between and 105 km above the photosphere for different models (Brown and McClymont, 1974; McClymont and Brown, 1974). Equally diverse values have been inferred from observations of synchronous chromospheric EUV bursts (Kane and Donnelly, 1971) on the one hand and from apparently behind-the-limb events (e.g. Datlowe, 1975) on the other.
Determination of the Height of Hard X-Ray Sources in the Solar Atmosphere by Measurement of Photospheric Albedo Photons