Defects in the Cholesteric Texture

Defects in the Cholesteric Texture

At intermediate concentrations, liquid crystalline DNA exists in a cholesteric lyotropic mesophase. This phase exhibits textures consistent with periodic variations in refractive index and fringe patterns with spacings of P/2 where P is the cholesteric pitch. The photomicrograph illustrated above exhibits refractive index variations due to the cholesteric pitch and liquid crystalline defects at the edges of the mesophase. The DNA concentration for this specimen is approximately 225 milligrams per millimeter, and the magnification is approximately 350x. The digital image presented above was originally recorded on Fujichrome 64T transparency film using a Nikon Optiphot-Pol microscope with crossed polarized illumination. Exposures were recorded about 2.5 f-steps under the recommended value given by an in-camera photomultiplier and were push-processed approximately 1.5 f-steps in the first E-6 developer.

© 1995-2013 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, software, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Thursday, Feb 26, 2004 at 12:41 PM
Access Count Since May 13, 2000: 27866