Raman vs. IR Spectroscopy: Key Differences, Applications, and Advantages

The figure on the right compares NIR gasoline data and data obtained with our Raman analyzer. NIR has very broad bands arising from overtones and harmonics that contain only subtle differences between different gasoline blends whereas Raman spectroscopy provides excellent spectral resolution of fundamental vibrations allowing for minimum component overlap and maximum component specificity. Raman spectroscopy has the advantage over infrared in that there is no interference from water so the probe can be directly inserted into a process stream. Infrared spectroscopy requires a sample conditioner. A single Raman system can be multiplexed up to 18 channels/streams. Because of the poor resolution of NIR analyzers, it is difficult to transfer chemometric models between instruments. However, models transfer easily with our Raman instruments and so additional models for new blends or components can be developed on our laboratory instrument and then be directly loaded onto our on-line process Raman analyzer.