Nuclear Screening and the Chemical Shift

If all the nuclei being detected in an NMR experiment (all protons in an organic ligand molecule, for instance) resonated at the same frequency, chemists would not be very interested because little information about structure. 

The inverse of the energy separation, AE, between ground and excited electronic states of the molecule. This means that there will be a correlation between NMR spectra and absorption in the visible and ultraviolet spectral regions. 

The relative electron density in p orbitals involved in bonding. 

The value of (l/r , the average inverse cube distance from the nucleus to the electronic orbitals involved. 

---