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Pulse sequence

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated July 18, 2023
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In Fourier transform NMR spectroscopy and imaging, a pulse sequence describes a series of radio frequency pulses applied to the sample, such that the free induction decay is related to the characteristic frequencies of the desired signals. After applying a Fourier transform, the signal can be represented in the frequency domain as the NMR spectrum. In magnetic resonance imaging, additional gradient pulses are applied by switching magnetic fields that exhibit a space-dependent gradient which can be used to reconstruct spatially resolved images after applying Fourier transforms.

The outcome of pulse sequences is often analyzed using the product operator formalism.

Graphical representation of a pulse sequence for a homonuclear NOESY experiment. The three bars represent three 90° pulses.
Graphical representation of a pulse sequence for a homonuclear NOESY experiment. The three bars represent three 90° pulses.
An INEPT NMR pulse sequence for a heteronuclear experiment. The thin bar denotes a 90° pulse, while the thick bar denotes a 180° pulse. INEPT is a common building block of NMR experiments to improve 15N signal.
An INEPT NMR pulse sequence for a heteronuclear experiment. The thin bar denotes a 90° pulse, while the thick bar denotes a 180° pulse. INEPT is a common building block of NMR experiments to improve 15N signal.
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This article is adapted from the Wikipedia article “Pulse sequence”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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