Experimental assessment of the effective-medium approach for disordered monolayers of particles with high scattering...

The validity of using an effective-medium approach (EMA) to model the reflectivity of a disordered monolayer of particles that scatter light significantly is tested experimentally. To achieve this, we measured the optical reflectivity versus the angle of incidence in an internal reflection configuration of a disordered monolayer of polymeric particles with negligible optical absorption and a diameter of about half a wavelength (size parameter of 1.2) deposited on a glass-air interface. We found a clear effective-medium film equivalence, even for low particle densities and for angles of incidence well beyond the critical angle, where light penetrates the monolayer less than a particle diameter.