View source for Small Angle X-ray Scattering of Single Network Gyroid (I4132) Photonic Crystals In Butterfly Wing Scales

Written by: Grant England
AP225 Fall, 2011
==Info==
Title: Small Angle X-ray Scattering of Single Network Gyroid (I4132) Photonic Crystals In Butterfly Wing Scales
Authors: Vinodkumar Saranathana, Chinedum O. Osujib, Simon G. J. Mochrieb, Heeso Nohb, Suresh Narayananf,
Alec Sandyf, Eric R. Dufresneb, and Richard O. Pruma
@Harvard: http://www.pnas.org/content/early/2010/06/11/0909616107.full.pdf

==Summary==
This paper describes the physical and optical characterization of the three dimensional photonic crystal structures found in a few different types of butterflies.  By using various measurement and modeling techniques, they were able to determine the crystal structure found in such butterflies and used in the creation of structural color in the insects used for communication and signaling.  The method for creating such structures could serve as an inspiration for methodologies to create artificial photonic crystal structures with the same symmetries.

==Methods and Results==
It was found that the butterflies exhibited a gyroid structure with approximately racemic chirality.  The gyroid is from the I4132 space group and is fabricated by the butterfly in its development first by creating a double gyroid structure which is more thermodynamically favorable and then letting one of the interpenetrating gyroid structures die and dissolve, leaving only the more optically favorable single gyroid.  Some of the different photonic crystal structures can be seen in the figure below with both optical and SEM images.

[[Image:butterflyscales.jpg]]

In addition a movie visualizing the gyroid structure can be found at this link:
http://www.pnas.org/content/suppl/2010/06/14/0909616107.DCSupplemental/SM01.avi

==Conclusions and Link to Soft Matter==