The determination of absorbance and scattering coefficients for photochromic composition with the application of the black and white background method

Abstract

Fresnel's postulates and equations of energy transfer, including approximate Kubelka – Munk theory, also allow the determination of other optical parameters for measured materials as for example absorbance coefficient k and scattering coefficients. In the case of colorants it is possible to determine molar coefficient ε0 by absorption spectrophotometry and Lambert – Beer Law from a calibration set with a different concentration of specific substance. If we use recommended solvents for the photochromic pigments, from the capsules the pigments not only flood out, but also use additives (HALS). This situation results in turbid solution, where use of Lambert – Beer Law is problematic from point of their turbidity. An advantage for the case of finalized photochromic pigments applied on the textile or other substrates in determination of absorption k and scattering s coefficients is the black and white background method.