title: Colors of transparent submicron suspensions on approaching the Rayleigh regime.
abstract: The features of scattered and transmitted light by dilute suspensions of transparent submicron particles are investigated both in the spectral and in the perceived colorimetric domains, as a function of effective particle diameter D, particle-host refractive-index mismatch m, and scattering angle θ. Our results show that the wavelength λ-dependence of the scattering and extinction cross sections remains quite similar well beyond the Rayleigh regime up to particle sizes of a few hundreds nm, but only for specific scattering angles that depend on D and m, and tend to 90° on approaching the Rayleigh regime. Close to this limit (D/λ<<1), a simple criterion that relates the perceived scattering color at θ=90° and the ratio of the sample extinction coefficients at two properly selected wavelengths is demonstrated. A comparison between computed and measured data is presented.
authors.affiliation: Light in Light Srl, Como, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Magatti
authors.forename: Fabio
authors.initials: F
authors.lastname: Ferri
authors.forename: Paolo
authors.initials: P
authors.lastname: Ragazzi
authors.forename: Marta C
authors.initials: MC
authors.lastname: Pigazzini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Averchi
authors.forename: Paolo
authors.initials: P
authors.lastname: Di Trapani