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Tunnel Effect in Quantum Science
Содержание
- 1. Tunnel Effect in Quantum Science
- 2. Tunnel effect is one of the most important manifestations of quantum mechanics
- 3. Classic analogy: full internal reflectionIn the geometric
- 4. Classic analogy: full internal reflection
- 5. Examples of tunnel phenomena: -decay of heavy
- 6. Scientists, who discovered the tunnel effect
- 7. Scientists, who discovered the tunnel effect
- 8. Cold emission of metal electronsCold emission currentE is the external electrostatic field
- 9. Cold emission of metal electrons
- 10. Oscillation of a particle between two potential
- 11. Oscillation of a particle between two potential
- 12. Tunneling in the periodic lattice; electron band formationOne-dimensional periodic lattice potentialEk0 is the bandwidth
- 13. Franz-Keldysh effectTunneling probability W(BC) from the valence
- 14. Tunneling in chemistry
- 15. Tunneling in chemistry
- 16. Tunneling in chemistry
- 17. Tunneling in chemistry
- 18. Single-electron tunneling
- 19. Single-electron tunneling(4)(2)ΔE = e(e/2±Q)/CCorrect formula:
- 20. Single-electron tunneling
- 21. Single-electron tunneling
- 22. Скачать презентанцию
Tunnel effect is one of the most important manifestations of quantum mechanics
Слайды и текст этой презентации
Слайд 3Classic analogy: full internal reflection
In the geometric optics sin(r) starts
to exceed 1 when n2 is low enough. Thus, refraction
becomes impossible.Actually, electromagnetic wave penetrates into the optically more dense medium at a distance of the wave length λ. It can be found by the indicated set-up when δ ≤ λ.
Hence, a massive particle (electron, proton, etc.) directly reveals its wave properties!
Слайд 5Examples of tunnel phenomena: -decay of heavy nuclei
Potential energy
of the particle inside and outside the atomic nucleus:
is
the probability of the -particle escape during the time unit
Слайд 10Oscillation of a particle between two potential wells
Separate wells
Coupled wells
Initially
the particle is in the left well
Слайд 11Oscillation of a particle between two potential wells
Results of calculation:
W(t)
is a probability of the particle to occur in the
left well at the moment tLimiting cases:
The particle spends equal times in both wells
The particle is predominately in the left well
Слайд 12Tunneling in the periodic lattice; electron band formation
One-dimensional periodic lattice
potential
Ek0 is the bandwidth
Слайд 13Franz-Keldysh effect
Tunneling probability W(BC) from the valence band AB into
the conductance band CD is proportional to exp{-c[εg]3/2/E}, where εg
is the forbidden-gap width. This is Zener effect. It changes the coefficient E of the light absorption in a semiconductor in the homogeneous electric field E. This is Franz-Keldysh effect.
