Nuclear Spin Populations and NMR Signal

Nuclear spin populations help explain why NMR signals appear. In a magnetic field, nuclei can occupy a lower energy spin-up state or a higher energy spin-down state. Near absolute zero, most nuclei stay in the lower energy state.

As temperature rises, thermal collisions spread the spins more even...

Near absolute zero temperatures, in the presence of a magnetic field, most nuclei prefer the lower energy spin +½ state to the higher energy spin −½ state.

At room temperature, the energy from thermal collisions distributes the spins more equally between the two states, as described by the Boltzmann distribution equation.

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