In Fourier Transform NMR spectroscopy and imaging, a pulse sequence describes a series of radio frequency

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

 pulses applied to the sample, such that the free induction decay

Free induction decay

In Fourier Transform NMR, free induction decay is the observable NMR signal generated by non-equilibrium nuclear spin magnetisation precessing about the magnetic field ....

 is related to the characteristic frequencies of the wanted signals. After applying a Fourier Transform

Fourier transform

In mathematics, Fourier analysis is a subject area which grew from the study of Fourier series. The subject began with the study of the way general functions may be represented by sums of simpler trigonometric functions...

, the signal can be represented in the frequency domain

Frequency domain

In electronics, control systems engineering, and statistics, frequency domain is a term used to describe the domain for analysis of mathematical functions or signals with respect to frequency, rather than time....

 as the NMR spectrum. In Magnetic Resonance Imaging

Magnetic resonance imaging

Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...

, additional gradient pulses are being applied by switching magnetic fields that exhibit a space-dependent gradient which can be used to reconstruct, after Fourier Transform, spatially resolved images.

External links

• Pulse sequences in the online textbook
• The Basics of NMR (by Joseph Hornak)