The optical constants of di-iso-octyl phthalate and di-n-butyl phthalate

Abstract

The optical constants-refractive index ( n) and absorptive index ( k) have been found for di-iso-octyl phthalate [C 6H 4(COO · C 8H 17) 2] and di- n-butyl phthalate [C 6H 4(COO · C 4H 9) 2] for a wave-length range extending from 2 to 16 μm. The absorptive index has been found by transmission measurements using a variable path length cell. Relative specular reflectances, at a near normal angle of incidence, were measured with distilled water as the reflectance standard. The reflectances and the measured k values were substituted into a form of the Fresnel equation to give the corresponding refractive index values. In the wavelength regions where the k value proved too great to be measured directly by the transmission technique the n and k values were found using a Kramers-Kronig dispersion analysis.