The refractive index measurements reported in the literature suggest that HKUST-1 is transparent in the visible region (400-800 nm), so where does the blue color arise from?
It could be Rayleigh scattering, that can appear in porous materials.
Light travelling through the material is diffused to different degrees depending on the wavelength, with blue light being diffused to a greater degree than yellow light.
This means that the object appears blue, just like the sky does.
Thanks Timothy that sounds very reasonable. But Rayleigh scattering strongly correlates with size and shape of the scatterer. So different powder forms could eventually have different colours
.
The amount of scattering strongly correlates with the size and shape of the scatterer, but the scattering will always be stronger towards the blue end of the spectrum and weaker towards the red end. This means there will always be a blue or blue-green colour, but it could vary from pale to intense blue. If it is Rayleigh scattering then if a white light is viewed through the material it will appear yellow or orange, while the object appears blue when viewed from the side.
- Badges
- Science topic