The Refractive Index of Liquids for X-Rays

The refractive index for x-rays was measured for several liquids by the method of total reflection. A monochromatic beam (λ=1.537A) was obtained by using a copper target in the x-ray tube and by selectively reflecting the beam from a calcite crystal. This beam was, in turn, reflected at a grazing angle from a thin film of the liquid being studied, spread on a plane glass mirror. As the index of refraction for x-rays is less than unity, the beam will be totally reflected at angles smaller than the critical angle, a sudden reduction occurring in the intensity of the reflected beam at the critical angle. Photographs, taken while the mirror was being rotated, showed such an edge. A discussion is given of the effects on the microphotometer curves of the slit width of the microphotometer, the width of the crystal slit, the rotation of the mirror and the finite width of the spectral line. From measurements of the curves, the values of δ, which is equal to 1-n, were obtained and compared with the values calculated by means of the simplified from of the Drude-Lorentz dispersion formula. The results are.---