1. T1 experiment - Inversion Recovery
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2. 5-Dec-18

3. 5-Dec-18

4. Given t= tp, what is the maximum signal intensity obtainable?
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5. Spin-lattice relaxation T1 Transition probabilities (see exersice 2.7)
Transition probability
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6. NMR SPECTROSCOPY - AN INTRODUCTION CHEMICAL SHIFT AND COUPLING
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7. 12/5/2018
Show a FT-transform
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EWH

8. 5-Dec-18

9. FIRST OBSERVATION OF A NUCLEAR MAGNETIC RESONANCE SPECTRUM
PURCELL and BLOCH
NMR-SIGNAL OF WATER
w = gB
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10. 1H-NMR SPECTRUM OF ETHANOL, WHAT DOES IT LOOK LIKE ?
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11. WHY DO WE OBSERVE THREE RESONANCE BANDS ?
THE ELECTRON MOTION GENERATES A MAGNETIC
FIELD AT THE NUCLEUS
THE MAGNETIC FIELD SENSED BY THE NUCLEUS IS THUS
MODIFIED;
BNUCLEUS =B0-BEl
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12. w = gB = gBnucleus = g(1-BEl/B0).B0 = g (1-s)B0
WE WRITE;
w = gB = gBnucleus = g(1-BEl/B0).B0
= g (1-s)B0
s defines the shielding constant
The electron densites around the three “groups” of protons in ethanol are different
Hence;
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13. Si CH RESONANCE FREQUENCY OF A NUCLEUS IS ALWAYS
MEASURED RELATIVE TO SOME REFERENCE FREQUENCY
THIS REFERENCE IS CHOSEN TO BE TMS (FOR 1H- OG 13C) Si CH 3
THE LARMOR FREQUENCY OF TMS IS DENOTED nREF
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14. THE RELATIVE FREQUENCY OF A RESONANCE CAN THUS BE WRITTEN
Dn = nSAMPLE - nREF
SINCE; n =g/2p.(1-s)B0
nS-nREF = g/2p.(sREF - sS)B0
To obtain a magnetic field independent chemical shift we devide by n0
(= gB0/2p)
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15. 5-Dec-18

16. II s f
- C = O ^ s ^ s
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17. What will be the power distribution Vs frequency ?
HOW CAN WE IRRADIATE A BROAD RANGE OF SPECTRAL FREQUENCIES?
What will be the power distribution Vs frequency ?
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18. Strong B1  short 900-puls  short tp  broad band excitation
FOURIER TRANSFORMATION
Strong B1  short 900-puls  short tp  broad band excitation
Weak B1  long 900-puls  long tp  selective excitation
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19. (Communication between nuclei via bonding electrons)
COUPLING CONSTANT
(Communication between nuclei via bonding electrons)
Chemical shift
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20. Chemical shift
WHY ?
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21. The magnetic dipole moment m of spin-half (1/2) nuclei may have two orientations in a magnetic field This will be discussed later when introducing the quantum mechanical concept) B0
”up” ”down”
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22. The spin-orientation of a neighbouring nucleus affects
the magnetic field seen by the other nucleus
What will be the number of HA molecules in I and II ?
NA(I)  NA(II)
Boltzmann distribution
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23. How will the 1H-NMR spectrum of the following molecular
Exercise 3.0A
How will the 1H-NMR spectrum of the following molecular
fragments look like ? Discuss
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24. QUANTITATIVE NMR PUT SOME DEMANDS ON TH Rf-PULSE
The power of the pulse must be homogeneously distributed
throughout the frequency domain
Frequency
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25. METABOLISME I CELLER
31P - NMR
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