FT-IR (infrared) and FT-NIR (near infrared) spectroscopy deal with specifc regions of the electromagnetic spectrum and unlike other techniques like Raman, these instruments can measure their entire range of wavelengths simultaneously. The techniques rely on the fact that molecules absorb specific frequencies that are characteristic to their structure. These frequencies are dictated by such things as the shape of the molecular potential energy surfaces, the masses of the atoms, and the associated vibronic coupling and can thus be used to characterize materials and systems. FT-IR and FT-NIR can be used on solid,liquid and gaseous samples.