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|Title:||ALS/CXRO Seminar - Prof. Helen Gleeson|
|When:||02/ 6/2014 2:00 PM - 3:00 PM|
|Description:||Date: Feb. 6 (thursday) 2PM, 2014|
2-400F Conf Room
Prof. Helen Gleeson
University of Manchester, UK
"Unraveling structures of liquid crystal phases via resonant x-ray scattering"
The use of resonant x-ray scattering to determine structures in liquid crystal systems is a powerful experimental technique that utilises ‘forbidden reflections’ to determine the subtle differences in interlayer orientation that can differentiate several smectic systems. The technique relies on the materials containing an atom to which the x-ray energy can be tuned, usually Sulfur or Selenium. Experiments are often carried out on free-standing films that provide a highly monodomain structure that allows high resolution measurements to be made, and hence structural details to be determined. However, it is also possible to use the technique on materials contained in a device geometry, allowing exploration of field-effects and dynamics.
This talk reviews the successful use of resonant x-ray scattering in the study of the ferroelectric, antiferroelectric and ferrielectric phases of liquid crystals. It describes high-resolution, resonant, polarized x-ray scattering experiments performed on free-standing films of several materials that exhibit remarkably wide ferrielectric phases. It also describes how resonant x-ray scattering on devices allowed a new field-induced phase to be discovered.