EXPRESS: Accurate Measurement of the Optical Constants n and k for a Series of 57 Inorganic and Organic Liquids for Optical Modeling and Detection

Optical and Chemical Characterization of Uranium Dioxide (UO2) and Uraninite Mineral: Calculation of the Fundamental Optical Constants

“…The values for n and k are also far greater than typical organic complexes with maximal measured k values in the 1 to 2 range. 41 As a first-order approximation, it is possible to calculate the frequencies of the TO and LO modes via the KKT calculated complex permittivity and following the mathematics outlined by Axe and Pettit. 31 Table 1…”

Influence of intermolecular interactions on the infrared complex indices of refraction for binary liquid mixtures

“…The measurement of the complex index of refraction of the liquid mixtures was performed as described in detail in a previous publication for neat species. 18 These vetted protocols are readily applied to the binary mix measurements: a wide range of cell path lengths are used to determine the k -vector spectrum as a single sample cell cannot usually yield a complete k -vector, because strong bands saturate in the long path cells, while weak bands are often obscured by noise in the short path cell data. From the multiple cell spectra, the resulting k -vectors are baseline corrected and then spliced together using selected bands over their linear domains to form a composite k -vector that is valid for both weak and strong bands, extending across the full spectral range of the instrument.…”

“…To this end, work has been undertaken in our laboratory to catalog the complex index of refraction for numerous liquids 18 that can provide an alternative approach to identifying unknown liquid substances. In the event of chemical spills, for example, liquids are more likely encountered as thin films (submicron to 100's of microns) on metallic or dielectric substrates whereby both the substrate as well as the liquid contribute to the composite reflectance signature.…”

“…19 The real, n(n), and imaginary, k(n), components of the complex refractive index, however, are a prerequisite to such calculations, which can be used to simulate the reflectance spectra and account for the multiple phenomena (reflection, refraction and absorption) that affect the spectral content of the light reflected from condensed phase materials deposited on different substrates. 24 To this end, work has been undertaken in our laboratory to catalog the complex index of refraction for numerous liquids 18 that can provide an alternative approach to identifying unknown liquid substances. In the event of chemical spills, for example, liquids are more likely encountered as thin films (submicron to 100's of microns) on metallic or dielectric substrates whereby both the substrate as well as the liquid contribute to the composite reflectance signature.…”

“…For solid materials, databases of reflectance spectra are often employed [12][13][14][15][16][17] whereas transmittance (absorbance) data are more commonly used for liquids. 18,19 Liquids, however, are seldom observed in the environment in pure bulk form except for bodies of water, and only seldom for most solids. Thus, for both solid-and liquid-phases, there has been an ever-increasing need to model, rather than measure, the reflectance (or emittance) spectra that can account for the sundry morphological forms that may exist in natural and industrial environments, including thin vs. thick layers, mixtures, particles, droplets, etc.…”