•Nuclear spin is characterized by a spin
number, I, which can be zero or some positive integer multiple of 1/2 (e.g.
1/2, 1, 3/2, 2 etc.). Nuclei whose spin number, I= 0 have no magnetic moment(m);eg. 12C and 16O
show no NMR signal. Elements such as 1H, 13C, 19F and 31P
have I=1/2, while others have even higher spin numbers:
•I=1 14N, 2H
•I=3/2 11B, 35Cl, 37Cl,
79Br,
81Br.
•As the values for I increase, energy
levels and shapes of the magnetic fields become progressively more and more
complex.
•