The anisotropy in the optical constants of quartz crystals for soft X‐rays

Andrle, A.
Hönicke, P.
Vinson, J.
Quintanilha, R.
Saadeh, Q.
Heidenreich, S.
Scholze, F.
Soltwisch, V.

DOI: https://doi.org/10.23689/fidgeo-4384
Andrle, A.; Hönicke, P.; Vinson, J.; Quintanilha, R.; Saadeh, Q.; Heidenreich, S.; Scholze, F.; Soltwisch, V., 2021: The anisotropy in the optical constants of quartz crystals for soft X‐rays. In: Journal of Applied Crystallography, 54, 2, 402-408, DOI: https://doi.org/10.23689/fidgeo-4384. 
 
Hönicke, P.; 1Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
Vinson, J.; 2National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, USA
Quintanilha, R.; 3ASML Netherlands BV (ASML), The Netherlands
Saadeh, Q.; 1Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
Heidenreich, S.; 1Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
Scholze, F.; 1Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
Soltwisch, V.; 1Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany

Abstract

The refractive index of a y‐cut SiO2 crystal surface is reconstructed from orientation‐dependent soft X‐ray reflectometry measurements in the energy range from 45 to 620 eV. Owing to the anisotropy of the crystal structure in the (100) and (001) directions, a significant deviation of the measured reflectance at the Si L2,3 and O K absorption edges is observed. The anisotropy in the optical constants reconstructed from these data is also confirmed by ab initio Bethe–Salpeter equation calculations for the O K edge. This new experimental data set expands the existing literature data for quartz crystal optical constants significantly, particularly in the near‐edge regions.


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 to 620 eV. The reconstructed anisotropy in the optical constants is also confirmed by ab initio Bethe–Salpeter equation calculations of the O K edge. image