Hyperfine splitting
When a spinning electron interacts with a magnetic nuclei that has a magnetic spin, splitting occurs. We are able to calculate how many splitting lines we will see for any unpaired species using 2nI + 1.
n – equivalent number of nuclei
I – quantum spin number {1/2, 1, 3/2….}
When there are n equivalent nuclei of spin I1 and another set of m equivalent nuclei of spin I2, we use:
[(2nI1 + 1)(2mI2 + 1)}
Hyperfine splitting determines the number of lines in the spectrum, not intensities.
For Example:

