1. ECE 874: Physical Electronics
Prof. Virginia Ayres
Electrical & Computer Engineering
Michigan State University

2. Lecture 06, 18 Sep 12
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3. Atomic hydrogen can only radiate or absorb energy in discreet packets:
Heat hydrogen gas, get atomic hydrogen (not H2) = 1 proton + 1 electron.
Atomic hydrogen can only radiate or absorb energy in discreet packets:
En = eV/n2, n = 1, 2, 3, ……
This formula can also be used as an approximation for systems that are like hydrogen, such as excitons.
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4. Quantization of angular momentum
Ln = m0vrn = nhbar, n = 1, 2, 3, ……
Charge: Coulomb force
Motion: Centripetal force
Eliminate v, get expression for rn in terms of integer n
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5. Now get an expression for total energy En:
Energy due to motion
Get v in terms of rn from force balance (not L quantization). Reason: that’s how PE is written.
Energy due to charge
Now substitute for rn on previous slide to get En in terms of integer n
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8. This is the predicated ground state energy level.
What you can observe are transitions, e.g., E2 – E1:
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13. Chp. 02: 3 important examples of electron showing wavelike properties
Free electron
An electron between scattering events during transport in a semiconductor is often nearly free
Motivation: low heat transisotrs
Electron in an infinite potential well
Electron in a finite potential well
Pr. 2.7: Electrons in a triangular well = realistic
Motivation: these are all about Quantum well lasers:
Arai article:
Transitions between quantized energy levels DE = hc/l : what you see is light of precise wavelength l
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14. Approach: conservation of energy applied to wavelike electrons
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15. Approach: conservation of energy applied to wavelike electrons/particles:
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16. Approach: conservation of energy applied to wavelike electrons
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17. Approach: conservation of energy applied to wavelike electrons
VM Ayres, ECE874, F12