Optimisation of through-vial Raman analysis of turbid samples by modelling the Raman intensity-depth decay response.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Raman spectroscopy offers non-destructive chemical analysis through containers.
• Signal attenuation and vial interference degrade data quality in turbid samples.

Purpose of the Study:

• To investigate depth-dependent Raman intensity decay in turbid liquid suspensions.
• To develop a predictive framework for Raman signal attenuation.
• To enable quantitative through-container Raman analysis.

Main Methods:

• Utilized polystyrene (PS) particle suspensions as a model for turbid liquids.
• Applied Mie scattering theory and the Beer-Lambert law to model signal decay.
• Experimentally validated the framework using varying PS particle sizes and incremental depths with an 830 nm laser.

Main Results:

• Developed a framework to predict Raman intensity decay lengths based on Mie scattering and Beer-Lambert law.
• Experimental decay lengths for PS and water showed good agreement (within 20%) with predicted values.
• Validated the model's effectiveness across different particle sizes and depths.

Conclusions:

• The proposed framework accurately predicts Raman intensity decay in turbid samples.
• This enables optimized focal depth selection and consistent quantitative analysis.
• Facilitates advancements in through-container Raman applications in pharmaceuticals, materials science, and nanotechnology.