Date: Wednesday 14th of June 2017, 14:00.
Location: MB1012 (Minerva Building).

‘Self-assembled structural colour in nature’

by A. J. Parnell, University of Sheffield.

Abstract:

The diversity and vividness of structural colour in the natural world has been known going back as far as William Hook in the 17th century; what has only relatively recently been recognised is the elegance and finesse of the physics used to create these effects.^1,2 In this talk I will highlight some of the optical structures and effects responsible for colour in Butterfly scales, Bird feathers, and Beetle elytra (fig. 1) that have been studied to date.

We will also examine our current understanding of how these are created biologically and what control mechanisms nature has to produce such structures. In particular I will discuss the optical structure responsible for the colour of the Eurasian Jay feathers (Garrulus glandarius) where the nanostructure is produced by a phase-separation process that is arrested at a late stage; mastery of the colour is achieved by control over the duration of this phase-separation process.³

Figure 1. A single beetle scale from the Lepidiota stigma beetle along with the internal scale structure responsible for this ultra-white optical effect.

Figure 2. The colour derived from the x-ray determined structure (top panel) and the image of the area mapped (bottom panel) using x-ray scattering, showing the colour correlation.

1. Parker, A. R. 515 million years of structural colour. Journal of Optics A: Pure and Applied Optics (2000).
2. Vukusic, P., Hallam, B. & Noyes, J. Brilliant Whiteness in Ultrathin Beetle Scales. Science 315, 348–348 (2007).
3. Parnell, A. J. et al. Spatially modulated structural colour in bird feathers. Sci. Rep. 5, 18317 (2015).