Space-resolved chemical information from infrared extinction spectra

Area of Science:

• Materials Science
• Spectroscopy
• Optical Physics

Background:

• Accurate determination of the complex refractive index is crucial for material characterization.
• Existing methods often struggle with scattering effects and systematic experimental errors in extinction spectra.

Purpose of the Study:

• To present a new method for extracting the complex refractive index from extinction efficiency data.
• To simultaneously correct for scattering effects and systematic experimental errors in extinction spectra.

Main Methods:

• The method utilizes extinction efficiency data of dielectric spheres (homogeneous and layered).
• It corrects for baseline shifts, tilts, curvature, and scaling without requiring a reference spectrum.
• Fit functions used automatically satisfy the Kramers-Kronig relations.

Main Results:

• The method accurately reconstructs the complex refractive index for both homogeneous and layered spheres.
• It successfully determines sphere radius for homogeneous spheres and identifies substances in layers for heterogeneous spheres.
• Demonstrated accuracy and reliability using numerically computed and experimentally measured data.

Conclusions:

• The new method provides unambiguous interpretation of chemical information from complex refractive index data.
• It offers a robust approach for spectral correction, improving the accuracy of material analysis.
• Applicable to various dielectric sphere systems with minimal detector requirements.