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Liquid Crystal Alignment on Surfaces with Orientational Molecular Order: A Microscopic Model Derived from Soft X-ray Absorption Spectroscopy

  • Jan Lüning
  • Mahesh G. Samant
Chapter

Abstract

To investigate the microscopic origin of liquid crystal alignment on rubbed polymer surfaces several novel experimental techniques have been developed, which allow probing of the liquid crystal-polymer interface on a molecular level. The understanding of the alignment mechanism presented in this Chapter is based on the detection of the molecular orientation at rubbed polymer surfaces by surface sensitive, polarization dependent soft x-ray absorption spectroscopy resolving the near edge x-ray absorption fine structure (NEXAFS) of the absorption coefficient. NEXAFS spectroscopy is a powerful experimental technique for the investigation of ordering phenomena in thin films and at surfaces with element specificity, chemical selectivity, and sensitivity to the presence of orientational order. Its sampling depth can be tuned from the outermost surface layer only to a few ten nanometers deep into the film bulk. Also, this technique is especially powerful for the investigation of ordering phenomena in the absence of long-range order, as often the case in polymers, due to the local nature of the x-ray absorption process.

Keywords

Liquid Crystal Polyimide Film Electric Field Vector Liquid Crystal Molecule Total Electron Yield 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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© Springer-Verlag Berlin Heidelberg 2004

Authors and Affiliations

  • Jan Lüning
  • Mahesh G. Samant

There are no affiliations available

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