Direct measurement of the complex refractive index in the extreme ultraviolet spectral region using diffraction from a nanosphere array

Abstract

Using extreme ultraviolet (XUV) radiation from a high harmonic source, we observe diffraction from a single-layer self-assembled hexagonal array of 196±1.2 nm diameter polystyrene spheres. The Mie solution is used to predict the correct form factor for a single sphere and hence model the intensities of the observed diffraction peaks for the first three orders. By measuring the diffraction intensities in this way, we demonstrate a technique for obtaining the complex refractive index of a material at multiple wavelengths in the XUV from a single measurement. We present experimental results for polystyrene in the range of 25-30 nm. © 2008 American Institute of Physics.