Nuclear magnetic resonance spectroscopy

An analytical technique that detects signals from atomic nuclei in a magnetic field to reveal molecular structure, composition, and motion.

Nuclear spin: An intrinsic quantum angular momentum carried by certain atomic nuclei. Nuclear spin gives NMR-active nuclei magnetic moments that interact with applied fields.
Nuclear magnetic resonance: The resonant response of magnetic nuclei to radiofrequency energy in an applied magnetic field. Spectroscopy applies this physical phenomenon to chemical analysis.
Proton NMR: NMR spectroscopy that observes hydrogen-1 nuclei. Its chemical shifts, integrations, and splitting patterns are widely used to assign organic structures.
Mass spectrometry: An analytical technique that identifies ions by measuring their mass-to-charge ratios. It complements NMR with sensitive mass and fragmentation evidence rather than direct chemical-environment signals.
Larmor frequency: The precession frequency of a magnetic moment in an applied magnetic field. Resonance occurs when radiofrequency energy matches this field-dependent frequency.
Magnetic moment: A vector quantity that measures the strength and orientation of a system's magnetic properties. Nuclear magnetic moments couple to the external field and radiofrequency pulses.
Carbon-13 NMR: NMR spectroscopy that observes the carbon-13 isotope. It identifies distinct carbon environments in molecular structures.
Infrared spectroscopy: A technique that analyzes molecular absorption of infrared radiation associated with vibrational transitions. It reveals functional groups through vibrational bands instead of nuclear spin environments.
Chemical shift: The difference between a nucleus's resonance frequency and a reference frequency, usually reported in parts per million. Electron shielding shifts resonance positions, making chemical environments distinguishable.
Zeeman effect: The splitting of energy levels when a system is placed in a magnetic field. Field-induced nuclear energy-level separation sets the conditions for resonance.

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