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’s HandyRam™ 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. HandyRam™ 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.