*2.7.1 Principle*

The nuclear magnetic resonance (NMR) is one of the most useful and powerful techniques in determination of molecular structure. The principle behind NMR is that when a strong magnetic field and a radiofrequency transmitter are applied on sample molecules, the atomic nuclei of those molecules get excited and forms spectral lines in the spectrum [40].

#### *2.7.2 Instrumentation*

The components of NMR spectrometer are


#### *2.7.3 Applications*


*Spectroscopy and Spectrophotometry: principles and Applications for Colorimetric and Related… DOI: http://dx.doi.org/10.5772/intechopen.101106*

chemical structure and the dynamics of organic molecules in biological systems [35]. These structural studies provide an information related to functions of organic molecules such as amino acids, proteins, carbohydrates, and antibiotics such as ciprofloxacin, azithromycin and valinomycin.


### **2.8 Electron spin resonance spectroscopy (ESR)**

Electron spin resonance (ESR) or electron paramagnetic resonance (EPR) spectroscopy is an analytical technique for detecting and characterizing the paramagnetic species.
