NMR SpectrocopyNMR SpectrocopyNMR Spectroscopy is one of the most interesting ways of identifying substances. NMR uses alot of fancy processes to obtain spectra. The basis of NMR, though, is simple enough. Nuclei spin continually, and have varying spin states. They act like tiny bar magnets. When placed in a magnetic field, these nuclei can line up their spins with or against the field. When electromagnetic energy is applied at the right frequencies, the nuclei aligned with the field will absorb energy and flip from being oriented with the field to being oriented against it. The difference in energy between the two states is directly proportional to the magnitude of the magnetic field being applied.
When a nuclei absorbs energy, a signal is given in the NMR spectra and is recorded as a peak. Many NMR machines also use something called Fourier Transform analysis to integrate peaks. Nuclei of spin states of +1/2 and -1/2 will give peaks on NMR spectra. These peaks may be split due to the interaction of the atom with neighboring nuclei that are also spinning. Therefore, plots can be very helpful in helping chemists to know what a substance is, particularily for organic compounds, since many NMR machines (PNMR or CNMR) detect hydrogen or carbon nuclei.
Atoms with spin states of 1/2 will interact with proton peaks and split these peaks. The basic rule of thumb with splitting is the N+1 rule: you take the number of atoms doing the splitting and add one. That is the number of splits you should see in the peak. Here are some NMR spectra of my unknowns.
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This
image is fitting since alot of Physical Chemistry is based on the Heisenberg
Uncertainty Principle, which Einstein disliked but could never disprove!!
He said "God doesn't play dice..." Well, perhaps God doesn't,
but it looks as though there is incredible disorder in the world, that
somehow lends itself to order. For a poem on a related topic,
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