1. What is the origin of the nuclear magnetic dipole moment (m) and how is it oriented relative to an external magnetic field B0?
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2. From Quantum Mechanics (I = ½-particle; 1H, 13C,31P,…)z m q y f x
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3. Characterizing the motion of m in B0
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Characterizing the motion of m in B0
m = gL
L; angular momentum (spin)
= m x B
; torque
Exercise 1.1: Derive the above equation (qualitatively)
24-Nov-18
EWH

4. Solution Larmor Equation - the basic NMR equation
w = -gB
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5. 11/24/2018
Conclusion
THE LARMOR EQUATION (w = -gB) IS DERIVED FROM A CLASSICAL MECHANICAL APPROACH
THE SPIN MOTION IS WITHIN THE MHz-RANGE (Radio-frequencies)
24-Nov-18
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6. MOTION OF m IN A ROTATING FRAME OF REFERENCE
w; rotation frequency of the reference frame relative to the static frame
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7. mU  cos(w-w0)t mV  sin(w-w0)t
Exercise 1.4. Find the solution of the above equation in the rotating frame, (Note w0= -gB0)
mU  cos(w-w0)t
mV  sin(w-w0)t
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8. One dipole (mi) → Many dipoles ( )
Mxy = 0 !!!!!
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9. LINEAR POLARIZED FIELD [B1= B1cos(wt)]
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LINEAR POLARIZED FIELD [B1= B1cos(wt)]
Rf-irradiation
Conclusion:
A LPF is composed of two opposite rotating fields
24-Nov-18
EWH

10. RFR Application of an rf-pulse along the u-direction (Why and what effect ?)
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11. Excersize 1.5: What effect will B1have on the magnetization when on resonance (w0 = w) ? Discuss
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12. a B1
The magnetization is rotated an angle a during the duration t of the rf-pulse
Show experiment !
24-Nov-18

13. Decaying FID? – show experiment
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14. Including (phenomenologicaly) relaxation terms in the Bloch equation (RFR):
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15. Bloch Equation (on resonance, after magnetization is rotated onto the v-axis)
Solution (after the magnetization is rotated into the uv-plane (w1 = 0); Exercise 2.2)
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16. Water Confined between Solid Glass beads - Experiment
24-Nov-18

17. Effect of various types of magnetic field inhonogeneities on the FID decay Let N(B) represent the number of spins experiencing a magnetic field B. Since w = gB, we may write dN = N(w)dw
What is the observable signal intensity M if ?
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18. What if N(B) =
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19. Why doesn’t the FID decay exponentially with time as expected from theory? (Perform a CPMG pulse sequence)
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20. Why does the FID decay faster (1/T2
Why does the FID decay faster (1/T2*) than what is predicted by the true spin-spin relaxation rate 1/T2?
FID
Homogeneous field
lnM
Inhomogeneous field
Time
24-Nov-18

21. Principles for Measuring T2
Spin gymnastics: Controlled sequence of rf-pulses
Hahn spin-echo: p/2-t-p-t-deteksjon
(p/2)-puls
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22. The basic (p/2)x – p-x spin-echo experiment
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23. Magnetization in the rotating frame
“100 meter”
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24. 24-Nov-18

25. EKKO
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26. SPIN-ECHO-EKSPERIMENT
1/T2+1/T2INH
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27. p/2-t-(p-t-deteksjon)n
CPMG-pulse sequence
p/2-t-(p-t-deteksjon)n
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28. T1-experiment
24-Nov-18