Nuclear Magnetic Resonance Spectroscopy The energy difference AE between nuclear spin states depends on the strength of the applied magnetic field Absorption of energy with frequency vconverts a nucleus from a lower to a higher spin state -AE=8.0 x 10-5 kJ/mol for magnetic field strength of 4.7 T a For field strength of 4.7 T a radiofrequency (rf)of v=200 MHz is required to bring 1H nuclei into resonance For a field strength of 4.7 T a radiofrequency(rf)ofv=50 MHz is required to bring 13C nuclei into resonance (c) (b) Strength of applied field,Bo The energy difference DE between nuclear spin states depends on the strength of the applied magnetic field ▪ Absorption of energy with frequency n converts a nucleus from a lower to a higher spin state ▪ DE = 8.0 x 10-5 kJ/mol for magnetic field strength of 4.7 T a ▪ For field strength of 4.7 T a radiofrequency (rf) of n = 200 MHz is required to bring 1H nuclei into resonance ▪ For a field strength of 4.7 T a radiofrequency (rf) of n = 50 MHz is required to bring 13C nuclei into resonance Nuclear Magnetic Resonance Spectroscopy