Visible Mie Scattering in Nonabsorbing Hollow Sphere Powders

Hollow silica nanoparticles (HSNP) with diameters comparable to visible wavelengths and with thin shells (< 15 nm) feature an unexpected color effect. Single particle and powder spectroscopy, as well as calculations based on Mie theory were used to investigate this phenomenon. The use of HSNPs increases the transport mean free path of light significantly, which reduces multiple scattering, and thus the Mie resonances become visible to the bare eye.