title: Measurements of optical properties of high-density media.
abstract: Measurements of optical properties (scattering coefficient mu(s), absorption coefficient mu(a), reduced scattering coefficient mu(s)', and asymmetry factor g) have been carried out up to a volume particle concentration of rho = 0.227. The results for mu(s) and mu(s)' show significant deviations from the linear dependence on rho as expected when the independent scattering assumption is fulfilled. The asymmetry factor also changed significantly. In contrast, the dependence of mu(a) remained linear even at the largest concentration investigated. The simple linear dependence of absorption on the chromophore concentration expected from the independent scattering assumption is thus applicable also to spectroscopic measurements of dense media. A comparison with an approximate theoretical model based on the Foldy-Twersky equation is also reported. The model provides a good description of the dependence of mu(s) on particle concentration.
authors.affiliation: Dipartimento di Fisica dell'Università degli Studi di Firenze and Istituto Nazionale per la Fisica della Materia, Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze, Italy. giovanni.zaccanti@unifi.it
authors.forename: Giovanni
authors.initials: G
authors.lastname: Zaccanti
authors.forename: Samuele
authors.initials: S
authors.lastname: Del Bianco
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Martelli
mesh_terms: D003198:Computer Simulation; D003720:Densitometry / Q000295:instrumentation* / Q000379:methods*; D005217:Fat Emulsions, Intravenous / Q000737:chemistry*; D007834:Lasers; D008863:Microspheres; D008962:Models, Theoretical; D055095:Optics and Photonics; D010316:Particle Size; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity
chemical_list: D005217:Fat Emulsions, Intravenous