Difference between revisions of "NMR Theories"
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# only hydrogens are seen | # only hydrogens are seen | ||
# there are only three peaks | # there are only three peaks | ||
− | # the areas under the peaks are directly proportional to the concentrations of the hydrogens in ethanol i.e. the areas are 3:2:1 | + | # the areas under the peaks are directly proportional to the concentrations of the hydrogens in ethanol (i.e. the areas are 3:2:1) |
# two of the peaks are split into multiplets, while the third is a singlet | # two of the peaks are split into multiplets, while the third is a singlet | ||
# the intensity of the spectrum depends on the power of the rf pulse | # the intensity of the spectrum depends on the power of the rf pulse |
Revision as of 11:37, 16 March 2020
Any successful theory must explain the observed facts. In NMR the fact is that when a sample of ethanol placed in the center of a strong magnetic field and pulsed with a narrow band of a specific radio frequency energy (rf), a reproduceable spectrum of peaks will be produced. This spectrum has the following properties that must be explained:
- only hydrogens are seen
- there are only three peaks
- the areas under the peaks are directly proportional to the concentrations of the hydrogens in ethanol (i.e. the areas are 3:2:1)
- two of the peaks are split into multiplets, while the third is a singlet
- the intensity of the spectrum depends on the power of the rf pulse
- the distances between the peaks changes depending on the strength of the magnetic field
- the sizes of the multiplets do not change with the strength of the magnetic field
There are two main ways that these facts can be explained: One way looks at the absorbance of photons by atomic nuclei, while the other looks at absorption of rf energy by the magnetic fields of a sample.
List of topics in this section
- NMR of solids - it is still fundamentally NMR, but the technical challenges of having a solid vs a liquid need a whole section to describe the theory