NMR

Physics Behind NMR

Video Visualization

NMR places paramagnetic isotopes in a magnetic field $B_0$. Radio waves of frequency ${\nu }_r$ 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. $\nu$ is then extracted from this, and depending on the species present, there is a certain shift in $\nu$ in ppm relative to irradiating frequency $v_r$. 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

• Lamor Precession
• Lamor Frequency
• Ansiotropic Effect

Common Isotopes Used

• ${}_{}^{}{}_{}^1\mathrm{H}$
• ${}_{}^{}{}_{}^{13}\mathrm{C}$

Application

1H NMR

13C NMR