X-ray standing waves and scanning electron microscopy — Energy dispersive X-ray emission spectroscopy study of gold nanoparticles

A systematic characterization of mono-disperse nanoparticles with nominal diameters of 25 nm, 46 nm, 73 nm, 100 nm, 115 nm, and 250 nm was performed using X-ray standing waves (XSW). The samples were prepared on Si-wafer pieces and analyzed at DELTA synchrotron facility at beamline BL8 under grazing incidence geometry of the primary radiation. Additionally, SEM-EDX inspections of single particles as well as population-density checks were conducted. Particles with smaller diameters were able be characterized by XSW while the larger ones were not completely covered by the interference field produced by the provided 15 keV monochromatic radiation of BL8. The results of the measurements were compared with those of numerical simulations. The extension of the interference field perpendicular to the Si-wafer reflector was determined to be 83 nm ± 4 nm.