Final answer:
Mid-IR spectroscopy, with its distinct absorption bands, is primarily used for qualitative analysis to identify substances. Meanwhile, NIR spectroscopy, with its high penetration depth and less distinct overtones, is typically used for quantification, especially in complex matrices.
Step-by-step explanation:
Mid-IR and near-infrared (NIR) spectroscopy are both used to study the vibrational modes of molecules, each giving distinct insights; this complexity arises from atom's rotation and vibration within the molecules. The choice between mid-IR and NIR depends on the specifics of the analysis.
Mid-IR spectroscopy, due to its high sensitivity and specificity, is mainly used for qualitative analysis. The absorption bands are very distinct and can be directly related to the vibrational modes of different functional groups in a molecule, hence allowing identification of substances.
On the other hand, NIR spectroscopy is typically used for quantification. The overtones and combinations of fundamental vibrations in the NIR region are less distinct than in the mid-IR region, therefore, it is less appropriate for qualitative analysis. However, the NIR region's high penetration depth and the relatively simple and quick preparation of the sample makes it suitable for quantification, especially in complex matrices.
Learn more about Infrared Spectroscopy