The refractive index of a y-cut SiO2 crystal surface is reconstructed from polarization dependent soft X-ray reflectometry measurements in the energy range from 45 eV to 620 eV. Due to the anisotropy of the crystal structure in the (100) and (001) directions, we observe a significant deviation of the measured reflectance at the Si-L2,3 and O-K absorption edges. The anisotropy in the optical constants reconstructed from these data is also confirmed by ab initio Bethe-Salpeter Equation calculations of the O-K edge. This new experimental dataset expands the existing literature data for quartz optical constants significantly, particularly in the near-edge regions.
@article{arxiv.2010.09436,
title = {The anisotropy in the optical constants of quartz crystals for soft X-rays},
author = {A. Andrle and P. Hönicke and J. Vinson and R. Quintanilha and Q. Saadeh and S. Heidenreich and F. Scholze and V. Soltwisch},
journal= {arXiv preprint arXiv:2010.09436},
year = {2021}
}