1. Electron Spin Resonance in Microwave Field
Fudan University Department of Physics
2019/8/28
Electron Spin Resonance in Microwave Field
Feng lei
2019/8/28

2. Fudan University Department of Physics
2019/8/28
Outline
Introduction
Microwave in waveguide
ESR
DPPH’s ESR in Microwave Field
Conclusion
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3. Introduction Paulli introduced electron spin in 1924.
ESR was invented by the Russian physicist Zavoisky in 1945.
Extended by a group of physicists at Oxford University in the next decade.
Electron spin resonance spectroscopy (ESR).
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4. Microwave in waveguide
Rectangular waveguide
a=23mm,b=10mm
Only TE10 is allowed in this waveguide when the frequency of Microwave is 9.845GHz.
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5. Electron spin Electrons also have spin as nucleus:
When in magnetic field:
Resonance absorption condition:
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6. a spin electron ≈ a magnetic dipole
Susceptibility
Physics view:
a spin electron ≈ a magnetic dipole
Radioactive field:
So macro-absorption is proportional to χ
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7. Bloch equation Relaxation time approximation
where γ = GHz/T, and
So dynamic susceptibility:
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8. Microwave in waveguide
Shorting piston
Max-Position(mm)
Min-Position(mm)
VSWR
78.02
88.7 40
98.62
109.0
37.5
119.9
129.42 43
139.5
149.97
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9. Microwave in waveguide
Attenuator:
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10. Microwave in waveguide
H-T
E-T
No. 1 2 3
Simulation
1(measurement)
-5.2mW
1.7mW
(32.7%)
1(calculation)
-1W
0.281W
(28.1%)
2(measurement)
1.5mW
(28.8%)
3.5mW
(67.3%)
2(calculation)
0.242W
(24.2%)
0.673W
No. 1 2 3
Simulation
1(measurement)
-5.2mW
1.7mW
(32.6%)
1(calculation)
-1W
0.438W
(28.1%)
2(measurement)
1.95mW
(37.5%)
2.20mW
(42.3%)
2(calculation)
0.416W
(41.6%)
0.569W
(56.9%)
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11. Microwave in waveguide
M-T
No. 1 2 3 4
Simulation
1(measurement)
-5.2mW
1.79mW
(34.4%)
0mW
1(calculation)
-1W
0.315W
(31.5)
0.303W
(30.3%) W
(0.3%)
2(measurement)
1.7mW
(32.7%)
1.12mW
(21.5%)
2.22mW
(42.7%)
2(calculation)
0.275W
(32.3%)
0.254W
(25.4%)
0.458W
(45.8%)
3(measurement)
2.08mW
(40%)
3(calculation) W
(0.26%)
0.413W
(41.3%)
0.487W
(48.7%)
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12. Microwave in waveguide
Expand with plane wave
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13. Microwave in waveguide
Why it is so magic?
Power flow Ey Ez
Bx By Bz
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14. ESR
Experiment system
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15. ESR
Signal
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16. ESR
Image Processing
For resonator:
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17. ESR Slope ratio of first derivative of peaks
Signal First derivative Second derivative
Slope ratio of first derivative of peaks
Theoretic B/A: Lorentz 4 Gauss 2.2
No. 1 2 3
B/A
1.06
4.48
3.15
0.789
6.81
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18. ESR
Mixed Curve
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19. ESR If this interpretation is right:
This dissipation is fractional but important.
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20. Conclusion
Measurement and Simulation of Transmission efficiency of attenuator, M-T, H-T, E-T.
Measurement of constant of TE10 in rectangular wave guide.
ESR of DPPH in microwave field.
ESR image processing and argument of absorption curve type.
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21. Thanks for your attention
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