X-ray diffuse scattering from thin polystyrene films

ORAL

Abstract

Diffuse x-ray scattering from silicon supported polystyrene films has been measured as a function of thickness. An x-ray standing wave method was used to distinguish scattering from the surface and scattering from density fluctuations within the interior of the film. The former is a measure of surface roughness, while the latter yields the compressibility, $\kappa { }_T$. Films thicker than $h \quad \sim $100 nm had bulk values for $\kappa { }_T$, while thinner films showed the empirical relation $\kappa { }_T(h)=\kappa _T^{bulk} \left( {1+\alpha \mathord{\left/ {\vphantom {\alpha h}} \right. \kern-\nulldelimiterspace} h} \right)^\delta $ with \textit{$\alpha $} = 20 ($\pm $1) nm and \textit{$\delta $ }= 1.6 ($\pm $1). The surface component of the scattering agreed with capillary wave theory for small $q$, but excess scattering appeared at larger $q, $which followed a power law, $S^\ast \sim \,q^{1 \mathord{\left/ {\vphantom {1 \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon }$. We attribute the excess scattering to static roughness from chain ends and loops near the surface.

–

Authors

  • Mrinmay Mukhopadhyay

    University of California, San Diego, CA 92093, Department of Physics, University of California at San Diego

  • Zhang Jiang

    University of California, San Diego, CA 92093, Department of Physics, University of California at San Diego, Sogang University

  • Sunil Sinha

    University of California, San Diego, CA 92093, Department of Physics, University of California, San Diego, La Jolla, CA-92093, USA., Dept. of Physics, Univ. of California San Diego, La Jolla, CA 92093, Department of Physics, University of California at San Diego, University of California, San Diego, Department of Physics, University of California San Diego, La Jolla, CA 92093, University of California, San Diego and Los Alamos National Laboratory

  • Laurence B. Lurio

    Northern Illinois University, DeKalb, IL 60115

  • Jarett Stark

    Northern Illinois University, DeKalb, IL 60115

  • Xuesong Jiao

    Advanced Photon Source, Argonne, IL 60439

  • Suresh Narayanan

    Advanced Photon Source, Argonne, IL 60439, X-ray Science Division, Argonne National Lab, Argonne, IL 60439, Argonne National Laboratory, Advanced Photon Source, Argonne National Lab, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, Argonne National Lab

  • Alec Sandy

    Advanced Photon Source, Argonne, IL 60439, Advanced Photon Source, Argonne National Laboratory, Argonne, IL-60439, USA., Advanced Photon Source, Argonne National Lab