NMR
#Chemistry
Physics Behind NMR
Video Visualization
NMR places paramagnetic isotopes in a magnetic field $\displaystyle B_{0}$. Radio waves of frequency $\displaystyle \nu_{r}$ are shot at the isotopes, causing them to precess. The precession induces a current in coils surrounding the atoms arranged as shown in the video. $\displaystyle \nu$ is then extracted from this, and depending on the species present, there is a certain shift in $\displaystyle \nu$ in ppm relative to irradiating frequency $\displaystyle v_{r}$. Hydrogen atoms have a higher Lamor frequency, or frequency of precession, if they experience a larger magnetic field, which is partially canceled out by electrons surrounding the hydrogen. Thus, "deshielded" hydrogens oscillate a higher frequency
Topics
Common Isotopes Used
- $\displaystyle \ce{{}^{1}H}$
- $\displaystyle \ce{^{13}C}$