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Title: Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy

Abstract

Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

Authors:
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Advanced Light Source Division; Materials Sciences Division
OSTI Identifier:
1163275
Report Number(s):
LBNL-6722E
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 25 ENERGY STORAGE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; molecular anisotropy effects, resonant x-ray absorption, resonant x-ray scattering, polymers

Citation Formats

Stone, Kevin H. Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy. United States: N. p., 2014. Web.
Stone, Kevin H. Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy. United States.
Stone, Kevin H. Mon . "Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy". United States. doi:. https://www.osti.gov/servlets/purl/1163275.
@article{osti_1163275,
title = {Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy},
author = {Stone, Kevin H.},
abstractNote = {Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.},
doi = {},
journal = {Physical Review B},
number = ,
volume = ,
place = {United States},
year = {Mon Jul 14 00:00:00 EDT 2014},
month = {Mon Jul 14 00:00:00 EDT 2014}
}