Inverse SORS for detecting a low Raman-active turbid sample placed inside a highly Raman-active diffusely scattering...

Area of Science:

• Spectroscopy
• Biomedical Optics
• Analytical Chemistry

Background:

• Spatially-offset Raman spectroscopy (SORS) is valuable for analyzing samples with subtle differences between surface and subsurface targets.
• Previous SORS applications have demonstrated broad utility, often requiring analysis of targets several millimeters deep.

Purpose of the Study:

• To assess SORS feasibility for detecting low Raman-active turbid samples within highly Raman-active, diffusely scattering matrices.
• To determine the optimal probing depth for tissue detection within paraffin using SORS.

Main Methods:

• Paraffin-embedded chicken muscle tissue blocks were used as model samples.
• SORS measurements were performed to evaluate signal recovery at varying depths.
• The effect of tissue section thickness on probing depth was investigated.

Main Results:

• Tissue Raman signatures were best recovered at a depth of approximately 1 mm beneath the paraffin surface.
• Signal quality decreased significantly beyond 1 mm depth.
• Increasing the thickness of embedded tissue sections enhanced the achievable probing depth.

Conclusions:

• While the achievable probing depth is less than in some prior SORS studies, it remains sufficient for specific applications.
• SORS demonstrates potential for analyzing low-concentration targets within complex scattering media.
• The study highlights the importance of sample geometry and matrix properties in SORS analysis.