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Updated: Jan 12, 2026
09:26
Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
10.4K
Optical origins of central circular reflections in spherical colloidal clusters
Ryosuke Ohnuki1, Yukikazu Takeoka2, Shinya Yoshioka1
1Department of Physics and Astronomy, Faculty of Science and Technology, Tokyo University of Science, Yamazaki, Noda, 278-8510, Japan.
Journal of Colloid and Interface Science
|October 31, 2025
Summary
Structural colors in spherical colloidal clusters arise from two distinct optical processes. Researchers used microscopy and simulations to reveal surface reflection and substrate-reflected light with Bragg diffraction as key mechanisms.
Area of Science:
- Materials Science
- Optics
- Condensed Matter Physics
Background:
- Spherical colloidal clusters exhibit structural colors via optical interference.
- A central reflection spot is observed in these clusters, explained by periodic layers in onion-like structures.
- Similar spots in non-onion-like clusters require further optical mechanism clarification.
Purpose of the Study:
- To investigate the origin of circular reflection spots in spherical colloidal clusters.
- To elucidate the optical mechanisms responsible for structural coloration in diverse cluster architectures.
- To provide design principles for spherical structural color materials.
Main Methods:
- Optical microscopy for visual observation of reflection spots.
- Geometrical analysis to understand light path and interaction.
- Numerical simulations to model optical phenomena within clusters.
Main Results:
- Two distinct circular reflection spots with different radii are generally observed.
- One spot originates from direct reflection at the cluster surface.
- The second spot results from spectral filtering via Bragg diffraction and substrate reflection.
Conclusions:
- Two fundamental optical processes govern the observed spots and structural colors.
- Bragg diffraction from face-centered cubic lattices plays a key role in spectral filtering.
- Understanding these mechanisms enables the design of advanced structural color materials.
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