1. NMR-spectroscopy Kjernemagnetisk resonans
History
Physical requirements
Principles
Theory
Interpretation of spectra

2. History 1946: NMR discovered 1949: Chemical shift
1953: First commercial high resolution instrument
1960: Structure determination of organic molecules
1970: FT-NMR
1971 – 75 : 2D-NMR
1973: MR-tomography

3. An example

4. Schematic diagram of NMR

5. Physical requirements
1.Nuclear spin
(12C and 16O
are NMR silent)
Magnetic moment
2. Magnetic field
Number of spin states in the presence of a magnetic field = 2I +1
1H and 13C # spin states = 2
2H # spin states = 3

6. ν = frequency, B0 = applied magnetic field, γ = magnetogyric ratio
ΔE = hν ν = γB0/2π
ν = frequency, B0 = applied magnetic field, γ = magnetogyric ratio

7. N1 = number of nuclei in the α state
N1/N2 is given by Boltzmann’s distribution:
At 60 MHz: excess in α state is 9 nuclei in a population of 2 million.
The N1/N2 ratio increases with increasing B0.

8. Net magnetisation

9. Net magnetisation vector

10. FT-NMR

11. Magnetic field data

12. Properties

13. Sample preparation

14. Chemical shift

15. Electron density

16. δ-scale
Tetramethylsilane, Si(Me)4 is used as reference in both 1H and 13C
TMS: - The nuclei are strongly shielded and appear to the right
H and 4 13C nuclei
- One singel peak
- Chemically inert
- Non toxic

17. Carbon 13 and proton

18. Integration

19. Integration
CW(1H): The area is proportional to the number of nuclei in the peak
FT(1H): Same as CW given that the relaxtion time is long enough (2-3 s)
FT(13C): Not commonly used due to slow relaxtion and large difference
in relaxtion rates for different 13C nuclei.