Highly reflective Cr/C-based multilayer X-ray mirrors for the wavelength λ = 4.47 nm

The structural and reflective characteristics of multilayer X-ray mirrors based on Cr/C, optimized for the spectral range of the "carbon transparency window" wavelengths of 4.4-6.6 nm, were investigated. It is shown that interlayer interfaces at the Cr-on-C boundary are more extended than those at the C-on-Cr boundary. Passivation of carbon layers with nitrogen enables a significant reduction in the size of the interlayer interfaces at the Cr-to-C boundary from 0.51 nm to 0.39 nm. The use of the specified interface engineering technique has made it possible to obtain a record value for the reflection coefficient of a Cr/C normal incidence multilayer mirror R = 20.2% at a wavelength of λ = 4.47 nm.