Chemistry Notes for B.Sc. and M.Sc.

The principal of NMR Spectroscopy states that the absorption of radiation in the radio frequency region occurs only by those atoms whose nuclear spin, I is non zero and the organic molecules containing these atoms are placed in external magnetic field.  In the presence of external magnetic field the number of possible orientations for nuclear spin states for NMR active nucleus are given by 2I + 1. Taking proton as NMR active nucleus with its nuclear spin, I = 1/2  The number of possible orientations for proton are as follows = (2 x 1/2) + 1 = 2  The difference between these two different spin states for proton is represented by ∆E which is given as follows:                                    ∆E = hν = h γ H 0 /2 π                                     ν  =  γ H 0 /2 π ∆E = energy differe...