The quantized difference between energy levels corresponding to different orientations of the nuclear spin Δ E = γ ℏ B {\displaystyle \Delta E=\gamma \hbar B} . The ratio of nuclei in the lower energy state, with spin aligned to the external magnetic field, is determined by the Boltzmann distribution . [6] Thus, multiplying the dimensionless g-factor by the nuclear magneton ( 6992315245125500000♠ 451 2550 (15) × 10 −8 eV · T −1 ) and the applied magnetic field, and dividing by Boltzmann's constant ( 6995861733030000000♠ 3303 (50) × 10 −5 eV ⋅K −1 ) and the Kelvin temperature.

Many peaks in NMR spectra appear as symmetric patterns called doublets, triplets, quartets, quintets, etc. When you see these patterns it tells you about the number of adjacent (usually on the carbon next door to that bearing the absorbing hydrogen(s)), but different hydrogens. In simple spectra such as those we will be studying in organic chemistry lab, the number of peaks you see is one more than the number of adjacent, but different hydrogens. This is the so called n+1 rule . Different means that the adjacent hydrogens have a unique magnetic environment and absorb at a distinct frequency compared with the hydrogens in question. For example, consider bromoethane (structure given below).