Estimated permittivity functions for NIR and SWIR absorbing dyes by inverse analysis of transmission spectra

Abstract

An inverse analysis of transmission spectra for near-infrared (NIR, 0.7–0.9 μm) and shortwave infrared (SWIR, 0.9–1.7 μm) absorbing dyes in solution is presented. This analysis employs a parametric model of transmission through a sample of finite thickness, where the permittivity function is represented parametrically by a linear combination of Lorentz oscillator models. The results of this analysis provide estimates of permittivity functions, which can be adopted as input data to other types of models, such as those for prediction of transmission and reflectivity spectra for composites containing mixtures of dyes and other materials. In addition, the results of this analysis should contribute to a database of estimated permittivity functions for practical analysis of spectra.

Keywords:

• Permittivity functions
• NIR/SWIR spectra
• inverse analysis
• IR absorbing dyes