Nuclear magnetic resonance T1 relaxation time definition

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SUMMARY

The discussion centers on the definition and implications of T1 relaxation time in nuclear magnetic resonance (NMR), specifically in relation to gadolinium ions (Gd3+) and water molecules. It is established that the fluctuation of the local magnetic field, primarily due to thermal motion and inter-molecular collisions, leads to T1 decay. The total magnetic moment of Gd3+ remains constant, but its interaction with surrounding water molecules changes due to these fluctuations, facilitating energy exchange with the lattice. The reference provided highlights the role of paramagnetic relaxation in this context.

PREREQUISITES
  • Nuclear Magnetic Resonance (NMR) principles
  • Understanding of T1 relaxation time
  • Knowledge of gadolinium ions (Gd3+) behavior
  • Concept of paramagnetic relaxation
NEXT STEPS
  • Study the impact of thermal motion on T1 relaxation in NMR
  • Explore the role of paramagnetic ions in NMR relaxation processes
  • Investigate the diffusion dynamics of water molecules in NMR studies
  • Review the section on "Paramagnetic Relaxation" from the provided NMR course link
USEFUL FOR

Researchers and students in the fields of chemistry and physics, particularly those focusing on nuclear magnetic resonance, molecular dynamics, and the behavior of paramagnetic materials.

xfshi2000
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Hi all:
I have one confused concept about T1 relaxation time in nuclear magnetic resonance field.
As we know, fluctuation of local magnetic field inside the sample causes T1 decay in the following RF excitation. Imagine one simple mode, near a gadolinium ion (Gd3+), there is one water molecule. For ideal case, there are no other atom or molecule. The whole system consists of the ion and single water molecule. We know total magnetic moment is fixed for Gd3+. Total magnetic moment include spin magnetic moment, spin-orbital magnetic moment, electron orbital magnetic moment, and ion rotation induced magnetic moment, et al. If total magnetic moment is contant, how can this ion generate a fluctuation of magnetic field in the site of water molecule? thanks

xf
 
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Mostly by thermal motion closer to or further from the water molecule. As the distance between the two changes the water molecule's local magnetic environment changes and the water becomes more likely to exchange energy with the lattice.

See http://www.chem.queensu.ca/Facilities/NMR/nmr/webcourse/t1.htm especially section "3- Paramagnetic Relaxation" at the bottom.
 
Last edited by a moderator:
DaleSpam said:
Mostly by thermal motion closer to or further from the water molecule. As the distance between the two changes the water molecule's local magnetic environment changes and the water becomes more likely to exchange energy with the lattice.

See http://www.chem.queensu.ca/Facilities/NMR/nmr/webcourse/t1.htm especially section "3- Paramagnetic Relaxation" at the bottom.

Thanks for your advice and answer. I found one possible answer. The only reason to make Gd3+ ion change its total magnetic moment is due to collision of inter-molecule(diffusion). You can imagine that in water solution, the average distance between two water molecules are 3x10^-10 meter. Violent frequent collision keep changing the direction of total magnetic moment. Now fluctuation of local magnetic field cause T1 decay. thanks again

xf
 
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