On the Absence of Red Structural Color in Colloidal Glasses

ORAL

Abstract

When a colloidal glass is illuminated, the short-ranged spatial correlations between neighboring particles can give rise to constructive interference for a particular wavelength. Unlike the structural colors arising from Bragg diffraction in colloidal crystals, the colors of these colloidal glasses are independent of angle due to the disordered, isotropic microstructure. We therefore call them ``photonic glasses.'' A similar coloration mechanism is found in the feathers of certain birds. However, there are few examples of red photonic glasses either in nature or in colloidal systems. Using scattering theory, we show that the absence of red photonic glasses can be explained by the wavelength-dependence of the single-particle scattering cross-section, which can override the interference condition set by the structure. We propose ways to overcome this obstacle, and we report on experimental methods to make non-iridescent, structural red color.

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Authors

  • Sofia Magkiriadou

    Department of Physics, Harvard University, Cambridge, MA, USA

  • Jin-Gyu Park

    School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA, Harvard University

  • Young-Seok Kim

    Korea Electronics Technology Institute, S.Korea

  • Gi-Ra Yi

    Department of Polymer Science and Engineering, Sungkyunkwan University, Suwon, Gyunggi 440-746, S.Korea, Sungkyunkwan University

  • Vinothan N. Manoharan

    School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA, Harvard SEAS and Physics, Harvard University, Physics Department and SEAS Harvard University, Harvard University, School of Engineering and Applied Sciences and the Department of Physics, Harvard, Harvard University, School of Engineering and Applied Sciences and Dept. of Physics