Modeling the polarized X-ray scattering from periodic nanostructures with molecular anisotropy
Christopher D. Liman, Thomas A. Germer, Daniel F. Sunday, Dean M. DeLongchamp, Regis J. Kline
We discuss a new technique to measure molecular orientation in nanostructures using resonant soft X-rays. This technique is based on a variable angle transmission measurement called critical dimension X-ray scattering that enables the characterization of the three-dimensional shape of periodic nanostructures. By using this technique at resonant soft X-ray energies with different polarizations to measure soft materials, we gain information about the preferential molecular orientations of these nanostructures. The information about shape and molecular orientation is convolved in the scattering and must be extracted by comparing it to simulated scattering and fitting using inverse iterative algorithms. We develop a computationally efficient Born approximation simulation that takes into account biaxial molecular orientation, and validate it by comparing it to a rigorous coupled wave simulation. We then analyze the ability of various sample models to generate unique best fit solutions by generating simulated parameter sets and fitting the resulting scattering. The interaction of the measurement geometry and the change in orientation across a periodic repeat unit leads to distinct asymmetry in the scattering pattern which must be considered to accurately fit the scattering.
, Germer, T.
, Sunday, D.
, DeLongchamp, D.
and Kline, R.
Modeling the polarized X-ray scattering from periodic nanostructures with molecular anisotropy, Journal of Applied Crystallography
(Accessed May 17, 2022)