Complex refractive index of pigment violet 19 (β- modification) was determined by means of an ellipsometric method within the visible spectral range. From the known complex refractive index and the particle size of the pigment, single-scattering properties (scattering and extinction efficiency, asymmetry parameter) were calculated for vehicles of different refractive indices employing an algorithm based on Mie-theory for spherical particles. These parameters were fed into a multiple-scattering model to investigate the dependence of reflectance of a semi-infinite film on particle size and refractive index of the embedding medium. Theoretically calculated results are in reasonable agreement with corresponding experimentally determined reflectance spectra of pigment violet 19 dispersed in different solvent- and water-based resin systems.
Wilhelm H. Kettler,
"Complex refractive index and color of quinacridone pigments", Proc. SPIE 4421, 9th Congress of the International Colour Association, (6 June 2002); doi: 10.1117/12.464517; https://doi.org/10.1117/12.464517