Figure 2.

Physical properties of the colloidal amorphous arrays. a) Scattering spectra of colloidal amorphous arrays composed 341 nm silica particles with different amounts of CB. The incident angle relative to the normal angle of the planar membrane surface was 0°. The measurement angle was also approximately 0° relative to the normal angle of the planar membrane surface. b) SEM image of the colloidal amorphous arrays composed of 341 nm silica particles of with 0.05 wt % CB. The CB is indicated by an arrow. Scale bar=100 nm. c) Optical photographs showing the color change with varying quantities of CB, and with the size of silica particles. d) The scattering spectra of the array of 341 nm silica particles with 0.05 wt % CB as a function of the measurement angle. The incident angle relative to the normal membrane surface was 0°. The measurement angle θ varied from 0 to 20, 30 and 45° relative to the normal surface. Inset: Plots of the position of the peak wavelength λ _max versus the measurement angle θ. e) Optical photographs of the colloidal amorphous arrays composed of 269 and 341 nm particles with 0.075 wt % CB at different viewing angles under diffusive lighting conditions.