Raman spectroscopy is a very attractive technique for in situ monitoring of remote environments with optical fibers. The major advantage of Raman over its vibrational counterpart, IR spectroscopy, is the use of visible radiation. Raman can be excited with visible light, which has a high transrmission in optical fibers. Furthermore, an important application of remote, optical fiber sensors is water quality analysis and water does not interfere with Raman spectroscopy. The advantage of Raman over other visible spectroscopies (fluorescence and absorbance spectroscopy) is the large amount of structural information about the analyte that can be gleaned from Raman spectra. Normal Raman, resonance Raman, and SERS fiber optic probes have been constructed and shown to provide good sensitivity in special cases. However, in many situations samples will contain fluorescent impurities or analyte concentrations that are too low to be detected with a probe based on normal or resonance Raman scattering.
Mullen, Ken I., Keith T. Carron