CHEM 281 Midterm: NMR Spectroscopy 1
13 Nov 2017
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1h 1 proton, 0 neutrons (odd number of protons) 13c 6 protons, 7 neutrons (odd number of neutrons) As the charged nuclei spins on the end of a bond it creates a small magnetic moment (think of a proton as a bar magnet) Normally, the magnetic moments are randomly oriented but if you place a molecule in an external magnetic field the magnetic moments will prefer to align with or against the applied magnetic field. The term spin state describes a situation where the magnetic moment is lined up with the applied field and spin state describes a situation where the magnetic moment is lined up against the applied magnetic field. Note: in 1h nmr spectroscopy we refer to hydrogen"s as protons. Therefore 1h nmr spectroscopy is also known as proton nuclear magnetic resonance spectroscopy. Graphically: sample is held inside magnet and pulsed with rf frequency radiation, absorbance is measured and a nmr spectrum is generated.
