Spectroscopic Techniques for Sample Qualification

The electromagnetic spectrum can be divided into distinct ranges from low-energy long-wave radiation to high-energy short-wave X rays and beyond (Fig. 3). From a spectroscopic point of view, the basis of these different ranges is the nature or type 

Electronic Transitions Vibrational Transitions Rotational Transitions 

Higher v, (k l) Higher Energy Lower v, (kf) Lower Energy  

The basic steps involved in identifying a sample using NIR will be illustrated using the SIMCA method, which is one of the popular methods for product ID. The 

SIMCA method relies on a pattern-recognition technique called principal component analysis (PCA). 

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