3. 3
NMR spectroscopy is the study of spin changes at the
nuclear level when a radiofrequency energy is absorbed
in the presence of magnetic field.
The energy required for NMR lies in the low
energy or long wavelength radio frequency.
4. 4
PrinciplePrinciple
Magnetic field is applied
Any proton or nucleus with odd
mass number
Its spin on its own axis and magnetic
moment is created with a frequency
called as precessional frequency
5. 5
This state is called ground state or parallel
orientation
In this state magnetic field caused by spin of
nuclei is aligned with externally applied
magnetic field.
Radiofrequency is applied (energy)
Absorption of energy, nucleus move
from G.S to E.S
6. 6
Results- spin reversal anti-parallel orientation
Application of radiofrequency is stopped
Nucleus returns to G.S or parallel orientation
11. 11
Theory of FT-NMRTheory of FT-NMR
Magnetic nuclei in magnetic field
Pulse of radio frequency is irradiated
Nuclei absorb some of the energy
Precess (spin) like little tops
12. 12
(signal) Free induction decay (FID)
is converted to spectrum
A complex signal is produced, then
decay as nuclei lose energy
13. 13
ADVANTAGES:-ADVANTAGES:-
• FT-NMR is more sensitive and can
measure more weaker signals.
• Dramatic increase in the sensitivity of
NMR measurements.
• Can be obtained with less than 5mg of
compound.
• The signal stand out clearly with almost
no electronic background noise
• Used in engineering, industrial quality
control and medicine.
14. 14
• The FT-NMR method also gives
improved spectra for sparingly soluble
compounds.
15. 15
Reference:-Reference:-
• Text book of pharmaceutical analysis by
Ravisankar, page no: 6-2 to 6-4
• https://www.solairajananant/nmr-spectroscopy
• https://www.bijayauprety-nmr 41214142
• https://www.pci.tu.bs.de/aggericke/PC4/kap-i/ftnm
