In Fourier transform nuclear magnetic resonance spectroscopy, free induction decay (FID) is the observable NMR signal generated by non-equilibrium nuclear spin magnetization precessing about the magnetic field (conventionally along z). This non-equilibrium magnetization can be created generally by applying a pulse of radio-frequency close to the Larmor frequency of the nuclear spins.
If the magnetization vector has a non-zero component in the xy plane, then the precessing magnetisation will induce a corresponding oscillating voltage in a detection coil surrounding the sample.[1] This time-domain signal (a sinusoid) is typically digitised and then Fourier transformed in order to obtain a frequency spectrum of the NMR signal i.e. the NMR spectrum.[2]
The duration of the NMR signal is ultimately limited by T2 relaxation, but mutual interference of the different NMR frequencies present also causes the signal to be damped more quickly.
When NMR frequencies are well-resolved, as is typically the case in the NMR of samples in solution, the overall decay of the FID is relaxation-limited and the FID is approximately exponential (with the time constant T2 changed, indicated by T2*).[citation needed] FID durations will then be of the order of seconds for nuclei such as 1H.
Particularly if a limited number of frequency components are present, the FID may be analysed directly for quantitative determinations of physical properties, such as hydrogen content in aviation fuel, solid and liquid ratio in dairy products (time-domain NMR).[3]
Advances in the development of quantum-scale sensors, particularly NV centres, have enabled the observation of the FID of single nuclei.[4] When measuring the precession of a single nucleus, quantum mechanical measurement back action has to be considered. In this special case, also the measurement itself contributes to the decay as predicted by quantum mechanics.
^Joseph P. Hornak. "The Basics of MRI". Rochester Institute of Technology. Chapter 4: NMR SPECTROSCOPY.
^Cite error: The named reference Duer2004p43-58 was invoked but never defined (see the help page).
^Cite error: The named reference TODT2006 was invoked but never defined (see the help page).
^Cite error: The named reference SingleFID_Nature was invoked but never defined (see the help page).
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In Fourier transform nuclear magnetic resonance spectroscopy, freeinductiondecay (FID) is the observable NMR signal generated by non-equilibrium nuclear...
series of radio frequency pulses applied to the sample, such that the freeinductiondecay is related to the characteristic frequencies of the desired signals...
ranging from line lists that can be graphically displayed to raw freeinductiondecay (FID) data. Data is usually annotated in a way that correlates the...
value of T2*, which is the actually observed decay time of the observed NMR signal, or freeinductiondecay (to 1/e of the initial amplitude immediately...
emission that accompanies decoherence of the molecular ensemble. This freeinductiondecay occurs on a timescale of 1-100 microseconds depending on instrument...
of the freeinductiondecay signal. This is fundamentally a power relationship (amplitude squared) but often computed as an [rms]. For decaying signals...
magnetic resonance (NMR) spectrum is determined by the process of freeinductiondecay. This decay is approximately exponential, so the line shape is Lorentzian...
dephased after a period of time (due to freeinductiondecay) and also by applying a reversed magnetic gradient to decay the spins. No signal is produced because...
is used in magnetic resonance imaging. In 1950, spin echoes and freeinductiondecay were first detected by Erwin Hahn and in 1952, Herman Carr produced...
changes and takes advantage of the multiple dimensions available in a freeinductiondecay analysis. The application of the Morlet wavelet analysis is also...
{\displaystyle \theta _{E}} , (2) the recording of the time domain signal (Freeinductiondecay, FID) for a duration known as acquisition time a t {\displaystyle...
refocussing pulses placed between recording of successive points of the freeinductiondecay, in an analogous fashion to the spin echo technique in MRI, the chemical...
passes close to as they cyclotron. The resulting signal is called a freeinductiondecay (fid), transient or interferogram that consists of a superposition...
spectroscopy, e.g. infrared (FTIR). In NMR an exponentially shaped freeinductiondecay (FID) signal is acquired in the time domain and Fourier-transformed...
frequency (60–1000 MHz) pulse, a nuclear magnetic resonance response - a freeinductiondecay (FID) - is obtained. It is a very weak signal, and requires sensitive...
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signal generated by the rotating magnetization vector is called freeinductiondecay (FID). Another assumption we have made was the exact resonance condition...
This signal is called the freeinductiondecay (FID). In an idealized nuclear magnetic resonance experiment, the FID decays approximately exponentially...