Characterization of Sc/Mg multilayers with and without Co barriers layers for x-ray spectroscopy in the water window range

We characterize the nanoscale periodic Sc/Mg two-layer, Sc/Mg/Co trilayers, and the Sc/Co/Mg/Co quadrilayer designed as dispersive elements for x-ray spectroscopy in the nitrogen K range (390 eV). The samples are prepared by magnetron sputtering with Mg and Sc layers being a few nanometers thick and Co layers being of subnanometric thickness. We apply nondestructive (x-ray reflectivity and x-ray fluorescence in a standing wave mode) and destructive (transmission electron microscopy) techniques to obtain a relevant description of the deposited stacks. It turns out that a strong interdiffusion takes place in the two-layer leading to poor reflective properties. Interdiffusion also occurs in the trilayers and quadrilayer but between the Sc and Co layers. These systems can be considered as periodic ScCo/Mg two-layers with well-defined layers. As a consequence, the Sc/Co/Mg/Co multilayer is found interesting to use for spectroscopy as a reflectance of 32% is expected in the N K range in the water-window range.