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I am writing a lab report for class on PNMR experiment that we did. How come in this experiment we don't worry about the electron spins in our sample? Aren't the electrons affected by the PNMR machine as much as the protons? Isn't there electron proton spin interactions? For some reason, the lab only talks about the proton spins and does not mention the electron spins at all.

Since we did this at room temperature, does this mean that the electrons have so much energy that their spins doesn't even align with the permanent magnetic field, or are they all paired up with other electrons and therefore do not contribute much? I am very confused. Please help!!!

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up vote 2 down vote accepted

1st all electrons in "normal" matter occur in pairs with opposite spins, thus cancelling each other. Exeptions like stable radicals or O2, which has a triplet ground state, interact with the nuclear spins. Look for CIDNP, "Chemical Induced Dynamic Nuclear Polarisation".

In general electron magnetic contribution eg paramagnetism act to shorten the lifetime of the nuclear spin states, this is often used to enhance the sensitivity of NMR, when You get some rare earth salt infusion for brain scan. But electron spin/angular momentum can also make NMR impossible by line broadening.

2nd there is interaction between electrons and nulei, the coupling of the protons in different atoms of a molecule is mediated by the electrons of the bonds in between.

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