Refraction and Reflection of X-Rays
Following his discovery of X-rays in 1895, Röntgen made numerous investigations of their properties among which were a number of attempts to show the existence of refraction by prisms. All of these were unsuccessful as were attempts by others in the years following Röntgen’s work. It was not until 1919 that refraction was shown to occur with X-rays. Stenström1 found that reflections from crystal faces in the various successive orders did not occur at the angles predicted by the Bragg law if the wavelength of the X-rays was greater than about 3 Å. He interpreted this effect as being due to refraction of the X-rays as they enter and leave the crystal. If this is in fact the case then, of course, a similar effect of smaller size should occur at even shorter wavelengths. Careful measurements subsequently showed2 that the effect occurs at all wavelengths. Stenström was able to obtain values of refractive indices from his measurements (Section 8.2).
KeywordsRefractive Index Lattice Plane Critical Angle Photographic Plate Dispersion Theory
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