Raman Spectroscopy is a laser-based technique used to identify bulk* chemical compounds without touching or destroying the sample. A known-energy source, such as a 785 nm red laser, emits what are called excitation photons that interact with a substance’s chemical bonds – molecular vibrations resulting in energy transfer and scattered photons. The resultant, reflected, inelastically-scattered photons can have a different energy than the laser’s photons. The energy difference between the detected photons and the laser’s excitation photons is measured and used to generate a unique spectrum that acts as a chemical compound’s fingerprint. A Raman spectrometer has a library of such spectra and uses the spectra to compare a newly acquired sample spectrum to the spectra in the library; if there’s a match between the newly-acquired sample spectrum and a spectrum in the library then the system will identify the chemical compound being analyzed. Raman spectroscopy is very useful for identifying explosives, narcotics and many other substances. FFI offers the 100 Indicator™ from Serstech. Indicator™ is one of the smallest Raman systems available and is also MILSPEC qualified making it extremely rugged and even submersible in water up to one meter in depth. Indicator™ can identify thousands of substances including almost all explosives and narcotics.
* Bulk vs. Trace amounts. In our world a bulk amount is something that can be seen by the human eye; a trace amount is an amount that cannot be seen by the human eye.