Noninvasive analysis of thin turbid layers using microscale spatially offset Raman spectroscopy

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Confocal Raman microscopy struggles with highly turbid samples due to limited depth resolution.
• Microscale spatially offset Raman spectroscopy (micro-SORS) is a recent technique initially applied to cultural heritage.
• Diffuse scattering in thin layers hinders conventional noninvasive analysis.

Purpose of the Study:

• To extend the application of micro-SORS beyond cultural heritage.
• To demonstrate micro-SORS for analyzing thin, turbid layers in diverse materials.
• To establish micro-SORS as a viable noninvasive analytical tool for challenging samples.

Main Methods:

• Application of microscale spatially offset Raman spectroscopy (micro-SORS).
• Noninvasive detection of thin, turbid layers in polymers, wheat seeds, and paper.
• Invasive cross-sectional analysis for validation of micro-SORS findings.

Main Results:

• Successfully demonstrated the extended applicability of micro-SORS to turbid layers.
• Noninvasive detection of thin, highly turbid layers was achieved in polymers, wheat seeds, and paper.
• Micro-SORS results were confirmed by invasive cross-sectional analysis.

Conclusions:

• Micro-SORS is a powerful new Raman imaging modality.
• The technique overcomes limitations of conventional confocal Raman microscopy for turbid samples.
• Micro-SORS expands the toolkit for noninvasive, chemically specific analysis of diverse materials.