Cause of Chemical shift and its measurement in NMR
Upto now we have learnt some basic concepts behind NMR method. (Nuclear Magnetic Resonance) Now we will discuss how this NMR method helps in elucidation of molecular structure. We also know that this method tells about the environment around an atom in a molecule. Let us take a example of ethanol, In a same external magnetic field all the nuclei of hydrogen atom in ethanol must have to be precessed with equal precessional frequency but in real this is not happened. And this become a boon for NMR to detect difference between those hydrogen atoms positions in a molecule. Why all nucleus of a same atom do not precess with same frequency? The solution is that precession of a proton is depend on the external magnetic field , but inspite of same external magnetic field this difference is caused due to the shielding of valence electron around the nucleus in an atom. Electron being a charge particle when moves around a nucleus creates its own magnetic which become a