The effects of ion-polishing of the metal layers in W/Si and WRe/Si soft X-ray multilayer mirrors has been investigated, essentially distinguishing between effects at the layer directly treated by the ions, and effects at the interface underneath this layer in the stack. Planar transmission electron microscopy (TEM) and calibrated cross-sectional TEM showed counterbalancing effects, in the case of W/Si systems leading to an optimal soft X-ray reflectivity at 100 eV ion energy.
Surf. Sci.

Kessels, M. J. H., Verhoeven, J., Tichelaar, F. D., & Bijkerk, F. (2005). Ion-induced interface layer formation in W/Si and WRe/Si multilayers. Surf. Sci., 582, 227–234. doi:10.1016/j.susc.2005.03.019