Theory of midinfrared absorption microspectroscopy: I. Homogeneous samples.

Area of Science:

• Optics and Photonics
• Spectroscopy
• Materials Science

Background:

• Mid-infrared (IR) microspectroscopy is crucial for localized spectral analysis.
• A comprehensive theoretical model for IR microspectroscopy has been lacking.
• Understanding optical effects is vital for accurate data interpretation.

Purpose of the Study:

• To present a rigorous theoretical model for IR absorption microspectroscopy.
• To account for focusing effects, material dispersion, and sample geometry.
• To guide experimental methods and instrument design by quantifying spectral distortions.

Main Methods:

• Utilized Maxwell's equations to model beam propagation in IR microspectroscopy.
• Developed a theoretical framework to predict spectral response for homogeneous samples.
• Experimentally validated predictions using Fourier transform IR (FT-IR) microspectroscopy of photoresist.

Main Results:

• The theoretical model accurately predicts spectral response, considering optical effects.
• Experimental validation confirmed the model's predictions.
• Spectral distortions were quantified and found to be significant, often exceeding spectrometer noise levels.

Conclusions:

• Meaningful interpretation of IR microspectroscopic data requires understanding coupled optical effects.
• The developed model quantifies spectral distortions, crucial for accurate analysis.
• The model provides a framework to improve experimental methods and instrument design in IR microspectroscopy.