Energieabhängigkeit der Isochromatenstruktur von Wolfram im Energiebereich von 0,15 bis 6 keV

A systematic investigation is presented of the variation of isochromat structures with threshold voltage (quantum energies). With a double focusing X-ray monochromator highly resolved bremsstrahlung isochromats of tungsten are measured in the quantum energy range from 0.15 to 6 keV. Crystals with lattice constants up to about 50 Å could be used as dispersing devices. The initial parts of the isochromats (primary structure) turned out to be essentially independent of quantum energy. With the high resolution of the monochromator at quantum energies below 0.9 keV a fine structure in the primary structure of the corresponding isochromats could be observed. This fine structure is in qualitative agreement with a theoretical density of states calculated by Mattheiss. The following parts of the isochromats (secondary structure) depend strongly on quantum energy. These structures can be understood by the influence of characteristic energy losses in the target of the primary electrons.