Surface and interface characterization of Ru/C/Ru trilayer structure using grazing incidence X‐ray reflectivity and X‐ray fluorescence

In 8‐ to 20‐keV photon energy region, ruthenium and carbon thin films are used in multilayer monochromators. In the present study, this material combination is explored for X‐ray waveguide applications in hard X‐ray region. The structural parameters (thickness of each layer) of Ru/C/Ru waveguide structure are optimized to get maximum intensity enhancement of fundamental mode inside carbon guiding layer. A sample with optimized structural parameters is deposited using ion beam sputtering (IBS) technique and characterized using X‐ray reflectivity (XRR) and grazing incidence X‐ray fluorescence (GIXRF) techniques. The analysis suggests that the density of bottom Ru layer and carbon guiding layer is close to bulk density (~97% for Ru and ~95% for carbon), whereas density of top Ru layer is slightly lower (~93% of bulk density). A ~10% of thickness variation in top cladding layer along with marginal change in layer density deteriorate field enhancement in TE 0 mode by more than three times. Effect of thickness and density variation on waveguide (Ru [7 nm]/C [18 nm]/Ru [20 nm]) performance is discussed.