Evaluation of the refractive indices of pure organic dyes using binary mixture models

Abstract

The refractive index (RI) of organic dyes is highly important due to their applications in many optical and optoelectronic fields. Because the refractive indices of various organic dyes are unknown, in the present work, we have developed an easy and simple method to estimate the refractive indices of pure organic dyes using binary mixing rules. The refractive indices were measured at a temperature of 20 °C for a wavelength λ = 589.6 nm with an Abbe refractometer. The method was previously checked for two compounds with known refractive indices, Xylene and Fluorescein, both solved in ethanol. According to the acquired results, it can be stated that Arago-Biot and Gladstone-Dale mixing rules best check the RI. Afterward, this method was applied to the Phloxine B, diluted in ethanol, to determine its unknown RI. The obtained experimental refractive index data of Phloxine B + ethanol solutions at higher ethanol mole fractions were correlated satisfactorily with both models.