  Etched multilayers obtained by forming a laminar grating pattern within
interferential multilayer mirrors are used in the soft x-ray range to improve
the spectral resolution of wavelength dispersive spectrometers equipped with
periodic multilayers. We describe the fabrication process of such an etched
multilayer dispersive element, its characterization through reflectivity
measurement and simulations, and its implementation in a high-resolution
Johann-type spectrometer. The specially designed patterning of a Mo/B4C
multilayer is found fruitful in the range of the C K emission as the
diffraction pattern narrows by a factor 4 with respect to the non-etched
structure. This dispersive element with an improved spectral resolution was
successfully implemented for electronic structure study with an improved
spectral resolution by x-ray emission spectroscopy. As first results we present
the distinction between the chemical states of carbon atoms in various
compounds, such as graphite, SiC and B4C, by the different shape of their C K
emission band.
