Commercial NIR Instrumentation
Prior to World War II, the near-infrared (NIR) region was not considered to be particularly useful for organic compositional spectroscopy. The explanation for this line of reasoning seemed obvious. The NIR region consisted only of overtone and combination bands of fundamental molecular vibrations. It was also obvious that all these combination and overtone bands occur in a relatively narrow region (750-3,000 nm) as compared to the fundamental bands occurring at 2,800-50,000 nm. Thus it was observed that NIR bands are severely overlapped, difficult to resolve, and, once resolved, difficult to interpret. If the same information is obtained with better resolution in the infrared (IR) region, then why would any chemist be interested in the difficulties inherent with NIR spectroscopy?