I would be thankful to you all for the answer to my following curiosity:
Magnetic resonance imaging (MRI) or NMR exploits the proton spin of H-atom in water (mostly). Protons' spins are polarized/excited with the static magnetic field. But why the magnetic field does not affect the electrons orbiting the nucleus of H-atoms? Why are electrons not affected? Is it the case of intrinsic spin quantum numbers or gyromagnetic ratio? I mean, what is the reason of exploitation of protons' spins (but not electrons' spins) H-atoms in MRI/NMR?
Dear Bibek,
the electron is not affected by NMR because the magnetic dipole moment of the electron is by far greater than a proton (x658 stronger), due to the greater mass of the proton (x1836). This means that normally the electromagnetic waves (radio waves) can penetrate tissue normally to excite the H-nuclei, but to excite the electron magnetic moment the necessary energy is smth like x658 higher, becoming this way part of the microwave in the electromagnetic spectrum (they can penetrate only few tissue cm)---> result unsuitable for tissue study due to high energy deposit on the surface. I hope i was clear enough.
Have a nice day.
in electron spin resonance experiments the electron is affected by the magnetic field ->> Zeeman splitting
frequencies around 9.2 GHz (X-band) and magnetic fields of about 340 mT. The microwaves will be absorbed.
How do magnetic field affect water molecule ?what happen to proton spinning and electron spinning ?
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