Interface Structures of Ordered Fe and Gd Overlayers on W(110) from Photoelectron Diffraction

Full-solid-angle and site-specific photoelectron diffraction data have been obtained from interface W atoms just beneath $\left(1\times 1\right)$ Fe and $\left(7\times 14\right)$ Gd monolayers on W(110) by utilizing the core level shift in the W ${f4\mathrm{}}_{7/2}$ spectrum. A comparison of experiment with multiple scattering calculations permits determining the Fe adsorption site and the relative interlayer spacing to the first and second W layers. These Fe results are also compared to those from the very different Gd overlayer and from the clean W(110) surface.