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    In NMR and Infra Red spectroscopy both put different amounts of energy (different frequencies) into a sample and record the energy absorbed, won't you get IR peaks on an NMR spectrum and NMR troughs on an IR spectrum?

    eg. When you do NMR by analysing the energy amounts needed to "flip" hydrogen nuclei, won't you get resonance in the bonds absorbing energy as well? Or are NMR frequencies miles apart from the IR spectrum?

    Also, what does "chemical shift" mean on an NMR spectrum? I thought (as our teacher wrote to begin with) the frequency of the energy was on the bottom, as different "types" of protons changed spin at different energies.

    Thanks,

    mike
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    I think your very confused, NMR and IR are totally seperate and never interfere with each other because the conditions under which they take place are very different.

    IR uses infrared to make the bonds resinate and measures the absorbtion

    NMR uses a magnetic field to align the spins of the (usually) H protons and then a radio frequencey pulse is used, i cant quite remeber now, its been so long, but look here for an explanation of both : http://www.chemguide.co.uk/analysismenu.html#top
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    Oh. I thought we kept the magnetic field the same and changed the energy given to the sample, not the other way round, because the x-axis was labelled energy/frequency at first.
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    (Original post by mik1a)
    In NMR and Infra Red spectroscopy both put different amounts of energy (different frequencies) into a sample and record the energy absorbed, won't you get IR peaks on an NMR spectrum and NMR troughs on an IR spectrum?

    eg. When you do NMR by analysing the energy amounts needed to "flip" hydrogen nuclei, won't you get resonance in the bonds absorbing energy as well? Or are NMR frequencies miles apart from the IR spectrum?

    Also, what does "chemical shift" mean on an NMR spectrum? I thought (as our teacher wrote to begin with) the frequency of the energy was on the bottom, as different "types" of protons changed spin at different energies.

    Thanks,

    mike
    NMR uses high frequency radio waves I think, which are really far apart from IR (energy-wise) so they don't interfere.

    Each proton (hydrogen atom) in proton NMR spectroscopy is affected by it's chemical environment, eg - the atoms it is surrounded by, as the presence of external protons and electrons can affect the magnetic field around the proton. The "chemical shift" refers to these different chemical environments which produce slightly varying magnetic field energy differences between protons of opposite spin. This is why hydrogen atoms in different parts of a molecule show up with different chemical shifts.
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    (Original post by mik1a)
    In NMR and Infra Red spectroscopy both put different amounts of energy (different frequencies) into a sample and record the energy absorbed, won't you get IR peaks on an NMR spectrum and NMR troughs on an IR spectrum?

    eg. When you do NMR by analysing the energy amounts needed to "flip" hydrogen nuclei, won't you get resonance in the bonds absorbing energy as well? Or are NMR frequencies miles apart from the IR spectrum?

    Also, what does "chemical shift" mean on an NMR spectrum? I thought (as our teacher wrote to begin with) the frequency of the energy was on the bottom, as different "types" of protons changed spin at different energies.

    Thanks,

    mike
    Energy levels are subject to quantum mechanics. This means that a bond cant just absorb and lose photons of any given energy. The same applies to the atomic nucleus. This is why NMR and IR spectroscpy are extremely unlikely to interfere. Technically they could but the chance of it happening is less than winning the lottery a million times in a row.
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    So when the proton flips, why does it not flip back to the lower energy state and release the same amount of energy, cancelling any effect you would see?
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    because it is positronic, rather than photonic quanta...
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    (Original post by mik1a)
    So when the proton flips, why does it not flip back to the lower energy state and release the same amount of energy, cancelling any effect you would see?
    it does, and it is this emission of energy which is measured and used. it's an emission spectrum, not an absorption one. i think.
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    (Original post by mik1a)
    So when the proton flips, why does it not flip back to the lower energy state and release the same amount of energy, cancelling any effect you would see?
    I thought that was the idea. You impart energy into the protons and then measure the energy they emit while returning to their ground state...?

    I never need do anymore of that type of physical chemistry ever again!
 
 
 
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