Why do we need to use large magnets and not simply the earth's magnetic field to measure an NMR spectrum?
 

Why do we need to use large magnets and not simply the earth's magnetic field to measure an NMR spectrum?

Why do we need to use large magnets and not simply the earth's magnetic field to measure an NMR spectrum?
 

The Earth's magnetic field isn't strong enough.

Why do we need to use large magnets and not simply the earth's magnetic field to measure an NMR spectrum?
 

The magnetic fields used in NMR are also VERY homogeneous and directional which allows us to get a few of those little protons to line up just right so they split according to a boltzman distribution into the alpha and beta states, with and against the applied magnetic field respectively and this allows us to flip their spin states from low to high and measure the subtle differences in their energies when they relax.<br />
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