The complex refractive index measurement of liquids by a novel reflectometer apparatus for the UV-visible spectral range

A novel reflectometer has been developed for the determination of the complex refractive index of liquids. In this study light reflected from the prism-sample interface has been analysed using the Fresnel equations to obtain values of the refractive index and extinction coefficient for several non-turbid liquids. The instrument allows one to control the angle of incidence and the wavelength so that other methods such as Kramers-Kronig analysis or the attenuated total reflectance technique can also be used. The wavelength can be varied in the range 250-650 nm. Tests with a diversity of liquids (water, ethanol, lignin solution, and so on) proved the validity of the device. The reflectometer is expected to have applications in industrial analysis of liquids.