BRAINCAKE13C NMR Spectroscopy
13C NMR detects the 13C isotope, which makes up only about 1.1% of carbon atoms. This is enough to give a spectrum, although it takes longer to record than a 1H spectrum.
Each peak in a 13C NMR spectrum corresponds to one carbon environment. Carbon atoms in the same environment (equivalent carbons, related by the symmetry of the molecule) give one peak. So:
• the number of peaks = the number of different carbon environments
• the chemical shift of each peak shows what the carbon is bonded to
In the spectra you meet at A level, each environment appears as a single line, and peak heights are not used to count carbons.
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Key terms in this lesson
- chemical shift
- The position of a signal in an NMR spectrum, measured in parts per million relative to TMS, determined by how shielded the nucleus is by electrons.
More in Modern Analytical Techniques
- Gas Chromatography
- Retention Times
- Nuclear Magnetic Resonance
- Chemical Shift
- 1H NMR Spectroscopy
- Integration Traces
- Spin-Spin Splitting
- The n+1 Rule
All 15 lessons in Modern Analytical Techniques · All Edexcel A-level Chemistry topics