Noninvasive Analysis of Thin Turbid Layers Using Microscale Spatially Offset Raman Spectroscopy

Abstract

Here, we demonstrate, for the first time, the extension of applicability of recently developed microscale spatially offset Raman spectroscopy (SORS), micro-SORS, from the area of cultural heritage to a wider range of analytical problems involving thin, tens of micrometers thick diffusely scattering turbid layers. The method can be applied in situations where a high turbidity of layers prevents the deployment of conventional confocal Raman microscopy with its depth resolving capability. The method was applied successfully to detect noninvasively the presence of thin, highly turbid layers within polymers, wheat seeds, and paper. An invasive, cross sectional analysis confirmed the micro-SORS findings. Micro-SORS represents a new Raman imaging modality expanding the portfolio of noninvasive, chemically specific analytical tools.

Raman spectroscopy: techniques and applications in the life sciences

“…Microscope-based SORS (μSORS) has also recently emerged as an application of the SORS concept at smaller length scales [396], for measuring thin multi-layered samples such as painted layers and plant seeds [397]. Experimentally, this was carried out in a slightly different manner to standard SORS, by defocusing the objective to collect light exiting the sample from larger offset positions.…”

Development of deep subsurface Raman spectroscopy for medical diagnosis and disease monitoring

“…Pavel Matousek has worked at the Rutherford Appleton Laboratory in the area of vibrational spectroscopy for over 24 minimises contribution from interfering tissue fluorescence. Pavel Matousek has worked at the Rutherford Appleton Laboratory in the area of vibrational spectroscopy for over 24 minimises contribution from interfering tissue fluorescence.…”

In situ chemically specific mapping of agrochemical seed coatings using stimulated Raman scattering microscopy

“…However, conventional analytical tools fall short of this requirement. Various methods, including HPLC‐mass spectrometry measurement , Raman spectroscopy , X‐ray Micro‐CT , and near infrared hyperspectral spectroscopy have been utilized to analyze the distribution of agrochemicals on the seed surfaces. However, these techniques suffer from a number of drawbacks such as lengthy sample preparation of seed sections , loss of spatial resolution, long acquisition times or lack of chemical specificity for the AIs .…”

“…Various methods, including HPLC‐mass spectrometry measurement , Raman spectroscopy , X‐ray Micro‐CT , and near infrared hyperspectral spectroscopy have been utilized to analyze the distribution of agrochemicals on the seed surfaces. However, these techniques suffer from a number of drawbacks such as lengthy sample preparation of seed sections , loss of spatial resolution, long acquisition times or lack of chemical specificity for the AIs . Labeling of the AI molecules with fluorophores has also been used to evaluate seed coatings , however the low molecular weight of most AIs means that fluorescent derivatization has a direct impact on their chemical‐physical properties which makes interpretation of the results difficult and potentially misleading.…”