NMR 12 - Carbon

Carbon has three natural isotopes.

Carbon 12: 99% abundance, the one used in the definition of a mole.
Carbon 13: 1% abundances, the one used for NMR, has a spin of ½.
Carbon 14: Trace abundance, the one used for radiocarbon dating.

Carbon NMR is typically less sensititive than H NMR, meaning more scans are needed to achieve the same resolution. One reason is the low abundance of ¹³C, another is that carbon has a lower magnetogyric ratio - This reduces the resonance frequency (link) which reduces the population excess (link) which reduces the resolution.

For a given field strength, carbon resonance frequency is about 1/4 of protons. So in a 300 Mhz machine, with the magnetic field ajusted to show proton resonance at 300 Mhz, we would observe carbon resonance around 75 Hz. This makes observing carbon resonance fairly easy to do on a machine which already does hydrogen NMR. You just need to adjust the magnet to 4x its strength, or (as is done in practice) switch the RF transmitter a quarter of its frequency.

Carbon NMR also uses correlation charts:

Notice the much larger range, 0 - 220 ppm compared to 0 - 15 ppm for protons. This means the peaks in carbon NMR are very unlikely to overlap.

See if you can spot differences or similarities with H NMR, such as the relative positions of alkyl and vinyl groups. Electronegativity, hybridization and anisotropy effect carbon in mostly the same way as protons. But the shifts are typically greater because the effects go through less bonds. For example, C-F goes through one bond while H-C-F goes through two. This explains the longer total range of shifts.