Proton Precession in Hydrogen-Rich Liquids

[Anil Iype]

TL;DR Summary

Can somebody clear my doubt regarding the proton precession ?

When a hydogen rich is subjected to a strong magnetic field , the protons ( which has a magnetic moment) lines up along the applied field in a parallel or anti parallel state.
My doubt is that- protons ( Hydrogen ion) in a hydrogen rich liquid cannot exist as an ion in a liquid because it recombines with an electron and becomes an hydrogen atom.

so when the proton precess , does it mean the hydogen atom is precessing, ?
In the case of water , does it mean the water molecule is precessing?

 

[Dale]

Anything with a magnetic moment will precess. But we only care about the things that precess near our RF frequency (Larmor frequency). Usually we set the frequency so that we get only the protons. That is, the hydrogen nuclei.

 

[DrClaude]

To make sure that what @Dale wrote is correctly understood:

so when the proton precess , does it mean the hydogen atom is precessing, ?
In the case of water , does it mean the water molecule is precessing?

No. It is the spin of the nucleus of the hydrogen atom that is precessing.

As the nucleus of the (regular) hydrogen atom is just a proton, it is common in NMR to talk about that nucleus simply as the "proton," but that does not mean that it concerns a free proton.

 

[Anil Iype]

Anything with a magnetic moment will precess. But we only care about the things that precess near our RF frequency (Larmor frequency). Usually we set the frequency so that we get only the protons. That is, the hydrogen nuclei.

Thanks for the explanation

To make sure that what @Dale wrote is correctly understood:

No. It is the spin of the nucleus of the hydrogen atom that is precessing.

As the nucleus of the (regular) hydrogen atom is just a proton, it is common in NMR to talk about that nucleus simply as the "proton," but that does not mean that it concerns a free proton.

Thanks for the explanation