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From Detection to Protection: How Raman Spectroscopy Is Changing the Game

Two people in hazmat suits picking up a bucket containing unknown contaminants.
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You can’t clean up what you can’t detect. Whether it’s dealing with the aftermath of a chemical spill, checking food for adulteration, identifying an improvised explosive device (IED) or sanitizing a military conflict zone, the first step is always the same: to identify the hidden risks and neutralize them. However, detection and remediation become significantly more challenging and dangerous when the analyte is concealed within a container or obscured by a covering layer.


Enter spatially offset Raman spectroscopy (SORS), a game-changer in non-invasive chemical characterization. SORS, a technique gaining significant interest, enables optical probing of analytes through light-obscuring surfaces like paper, glass, plastic and fabric, making it invaluable in a variety of critical situations.


Scattered discoveries

Fundamentally, Raman spectroscopy works by measuring how the energy of incoming light changes when it interacts with a sample. Of the light that is scattered from the target, a small amount will change in energy. This (Raman) scattering provides a unique fingerprint that allows the sample's chemical composition to be determined precisely.


SORS takes this technique up a level, making it possible to characterize substances hidden from direct view. By comparing the signals from where the light collection optics are positioned and an additional “spatially offset” position, the system can obtain a clean spectrum of the contents, removing the influence of the barrier completely.


Typically, SORS can be used to analyze materials through containers up to 10 mm thick, with the success of the technique depending on the specific combination of the contents and the barrier.


Not all Raman spectroscopy is equal

The benefits of SORS with through-barrier measurements are that it creates a safe testing environment for the user, increases the speed of assessment of unknown chemicals to aid decision making and provides non-destructive and non-invasive testing, which helps with chain of custody issues. These benefits make SORS a safe and effective choice for many users in a diverse range of environments.


By packaging the technology into a portable, handheld device, users are able to work quickly and flexibly, speeding up their chemical testing. Additionally, the extensive chemical libraries within the device, routinely updated to enable the detection of emerging threats and narcotics, provides the user with rapid sample identification without the need for lab analysis.


Choosing the right laser wavelength matters too. A laser wavelength of830 nm helps to reduce fluorescence interference from materials such as drugs and narcotics significantly, enhancing performance compared to traditional 785 nm systems. Also, using an enlarged laser spot size minimizes the risk of igniting sensitive explosives during testing of suspected IEDs and abandoned ordnance.


For scenarios where risks can’t be fully mitigated, these devices can be remotely operated and fitted to various robotic platforms, providing added flexibility.


Future developments

There is no shortage of potential applications for Raman-based detection. This technology is already being used by customs and border protection agencies, law enforcement, hazardous materials (HAZMAT) teams, defense and security providers and within the food and environmental industry. The common denominator across these fields is the need for fast, safe, accurate and repeatable analysis with minimum physical interaction with samples.


A further variation of the base technique is surface-enhanced Raman spectroscopy (SERS). This highly sensitive technique enhances the Raman scattering effect of molecules using nanostructured materials. Studies and field trials show that SERS can detect low concentrations of chemical trace-level contamination, when used in combination with commercially available substrates. These promising results are paving the way for increasing the capability of the already highly performing SORS equipment. For example, detection of low concentrations of the narcotic fentanyl within a street drug sample, which is too low for normal drug detection techniques.


Pioneering safety and precision in Raman spectroscopy

Raman spectroscopy technology is evolving, and its impact on safety and accuracy across industries is undeniable. The ongoing advancements in SORS and SERS are setting new standards in chemical analysis.


Collective progress in this field, driven by industry leaders and researchers, ensures that Raman spectroscopy remains at the forefront of non-invasive chemical characterization. These innovations promise to open new frontiers in detection and analysis, ultimately contributing to a safer, more informed world.