The Quantum World
- the rest of the course.
Weve thought about fast things. Now I want to think
about small things.
In physics were used thinking of things like energy as
continuous. But some things are digitized, like
charge. 1e, 2e, 11e OK; 1.4e is not
Ive described an n-channel enhancement mode MOSFET,
since I enhance the minority concentration near OX when I
I can also build a p-channel depletion mode MOSFET.
- - trapped
The layer near OX
is already inverted
Ive mentioned the Shroedinger equation; now I need to
explain it, using energy conservation.
For simplicity let me assume I have a perfect travelling
= ei(kx - t)
If I want to measure energy, what can I do? Differentiate.
d/dt = -i ei(kx - t) = -i
Tunneling for E < U0
[ Does this mean you can magically throw a bowling ball
through the wall? ]
[ Ive drawn the same wavelength on either side. Is that right? ]
EX. L = 5 -1
Heres another way to think of the Compton wavelength.
What is the wavelength of a photon whose energy is
equal to the rest energy of a particle of mass m?
E = hc/ = mc2
= h/mc !
We studied the electron Compton wavelength (a couple
Energy Quantization in Atoms
Ill start with a planetary model, since that is what I was
told in grade school. And Ill start with hydrogen, the
Planck: Light is quantized, or
digitized, into chunks of nhf.
Bohr 1913: perha
Fri Sept. 6
Strange name: refers to physics 1900-1930!
Freshman or pre-med phys: Newton, Maxwell to
1900-1930: Newton/Maxwell usually OK, but only:
- slow stuff: v < c = 3 x 108 m/
Momentum. Since the time between two events
depends on the reference frame, you might suspect
that true momentum is not what you saw in freshman
physics. Einstein found the correct momentum is
p = mu
refers to a particle, not a
Ultimate Composition: What is everything made
Leptons such as the e- are elementary.
There are six leptons, plus their antiparticles.
These are not made of anything else.
m 200me , m 3500me. Otherwise quite similar.
Hadrons are made
Indeed, carbon-diamond is an insulator, and Si is a
semiconductor, as you know.
C = [He]2s22p2. You know the p-state has an
occupancy of 6.
In both C and Si, there are four valence electrons, as
The C or Si lattice with covalen
The importance of closed
E.g. He n=1 shell is full. Ne n=2 shell full.
For a closed shell m = 0 No net orientation.
Nature prefers spheres, like raindrops
Minimum surface-to-volume ratio.
Closed-shell elements, with
Understanding molecules experimentally: MOLECULAR
Molecules have two new ways to possess KE. Draw
Rotation about the CM.
L(molecule), not atom!
Vibration about COM.
Each of these modes will give me quantized energy