Measurements and calculations of flat and spherically bent mica crystals' reflectivity and using them for different applications in the spectral range 1-19 Å

Abstract

Crystallographic and dispersion characteristics of muscovite at different reflection orders (2 divided by 24) for (001) lattice planes were investigated theoretically. Measurements of integral reflectivity were done for (10 divided by 38) reflection orders by using Cu and Mo X- tube radiation. Experimental results were compared with calculations for perfect and mosaic crystals. The integrated reflectivity for spherically bent mica crystals with R equals 100 and 186 mm have been calculated for various reflection orders. The results of these calculations show that muscovite crystals can be used in high reflection orders for high-resolution spectroscopy only if the crystal perfection is high enough, which provides the narrow reflection curve widths. These theoretical considerations are supported by results obtained in various plasma spectroscopic experiments. Nearly perfect muscovite crystals have been shown by using Lang and section topographic techniques for both flat and spherically bent muscovite crystals respectively. The high-quality of such crystals was also demonstrated using the scheme of obtaining a `parallel' x-ray beam and x-ray microscope schemes. Possible applications of high-quality muscovite spherical crystals are discussed.