+- Discovery Gaming Community (https://discoverygc.com/forums)
+-- Forum: The Community (https://discoverygc.com/forums/forumdisplay.php?fid=4)
+--- Forum: Real Life Discussion (https://discoverygc.com/forums/forumdisplay.php?fid=16)
+--- Thread: Hmm, quantum physics? (/showthread.php?tid=113758)
Hmm, quantum physics? - kikatsu - 03-25-2014
Anyone here happen to know a thing or two about quantum physics? Specifically I am working with some stuff based off of Compton scattering, De Broglie wave matter, and well some other rather complex stuff that I am not too great with like Z scaling Bohr states.
I am just trying to get a better grasp of the stuff and some stuff I am working on is just kind of stumping me.
RE: Hmm, quantum physics? - Tachyon - 03-25-2014
Would be helpful, if you stated in which detail you have to know these things and whether you're familiar with the basics of quantum physics (consult wikipedia?).
Implying you know plenty about classic physics + waves, here's some basic stuff for you.
Search for "quantization of certain physical properties", "wave–particle duality", "principle of uncertainty", "quantum entanglement" in Wikipedia (found all of it there) for an introduction into the four basic principles of QP.
Next you should get familiar with the behaviour of quantum objects and energy (models of electrons in atoms and their energy states, absorption, elastic & inelastic scattering in general, light/photons). -> E=hf
A nice experiment with electrons on this topic is the photoelectric effect (->Einstein) [E=eU0 for photoelectrons]
Electrons in atoms - Franck-Hertz experiment
The amount of energy an atom absorbs is characteristic for that atom => Each atom absorbs a certain energy value
DeBroglie, Energy of a quantum object: E=hf, λ=h/p (h= Planck constant, p=impulse of photon)
Bragg: k*λ=2a*sinϑ (sinϑ = angle at which photon/wave approaches scattering surface, λ = wavelength, a = distance between layers of scattering surface)
Compton effect/scattering:
m*= E/c²= hf/c² (*mass of a photon)
Δλ = (h / m0e * c) * (1-cosφ)
-> Δλ that's the change of the wavelengh when a photon is scattered by an electron (that's the Compton effect/scattering)
-> h is Planck's constant
-> m0e is the rest mass of the electron that scatters the photon
-> c is the speed of light (constant)
-> cosφ is the cosine of the angle the photon approaches the electron with
Hopes this helps, feel free to ask about details about anything of the above.
RE: Hmm, quantum physics? - kikatsu - 03-25-2014
The Bragg formula actually plugs a hole in something I am working with, just about. The k, or n in some places I have noticed needs to be an integer based on the multiple of the wavelength of the radiation hitting it.
What I am working with now is something with neutrons that have been slowed to 3000 m/s , which are scattered by a crystal with 10^-10 m separation between the layers. I am trying to figure out the angle of the first consecutive scatter pattern.
I was able to get their De Broglie wavelength (I think) with λ=h/mv which should be (6.63*10^-34) / ((3000)(1.674*10^-27 kg)) which gets me 1.32*10^-10
Now I can plug that into the Brag equation and with a little rearranging I can get it down to 1351.68=sinϑ/n .... (need to solve for sinϑ ultimately)
sinϑ=nλ/2d ... (n*(1.32*10^-10) / ((2(10^-10)) is what I got that from
but that n is giving me trouble now, there must be a way to solve for it, I can't seem to figure that out though... that or I may have missed something.
RE: Hmm, quantum physics? - Tachyon - 03-25-2014
Well, incase you know the path difference of the waves, Δl = k * λ.
Other than that, the k simply describes which maximum of the intensity of reflected light (or in this case neutrons) you're looking at. For different values (positive integers) of k you get different sin(ϑ), which all belong to a particle of the same wavelength - Means: Depending on which maximum (intensity - for reflected neutrons, intensity of the neutrons in a place, as diagram y=intensity, x=angle) you're looking at you will get 1,2,3 for the 1st, 2nd, 3rd, maximum.