Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Maniax101 on 17/01/2011 10:56:45
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Hey.
A double question...
From what I understand, we "see" something because light, or a photon, hits an electron in an object, thus exciting it to a higher orbit, and when the electron "falls down" it gives away a photon that we then interpret.
What if we shoot photons at a single proton, or neutron? Will they bounce off of it, or what happens then?
Secondly, what if you shoot a single photon at, for example, an uranium atom that has lots of electrons and lots of shells. What if the photon (being so fast) does not excite the electron in the outmost shell, but hits one "further in". Would that turn the photon into some sort of pinball frenzy in there, or is it always the outmost electron that is affected. If so, why?
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Shoot a photon on a proton, and you have the definition of a Quantum Observation. The photon may become absorbed but more importantly, the proton will shoot off when being hit by the photon because of the Uncertainty Principle, so you may only see it for a fraction of a second.
Would that turn the photon into some sort of pinball frenzy in there, or is it always the outmost electron that is affected. If so, why?
Pinball frenzy?
Electrons do not orbit the nucleus, and anywhere (levels) an electron is in, is unique that no other electron can inhabit that level. If a photon reached an electron inside the atom, all you will have is a quantum leap, a shift in energy levels. Particles don't behave like pinballs or anything related as such.
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I type so fast I missed a word above and also made a typo. It's fixed now.
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State of the art Electron Microscopy can image atoms. An example is here...
http://www.sciencedaily.com/releases/2008/01/080122154357.htm
but if you search on Google you can find others.
It may be a bit simplistic to think of electrons bouncing like a pin ball but it is not far off the actual behaviour of electrons when imaging materials as is sometimes done with a Scanning Electron Microscope. One imaging technique is to utilise the electrons that are "back scattered" from the atoms at the surface, though it is more common to look at secondary emissions. An overview is here...
http://en.wikipedia.org/wiki/Scanning_electron_microscope
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In principle, a sufficiently brightly lit proton would be visible.
You would need to light it from both sides or it would get pushed out of view by proton pressure.
The intensity of light needed might be impractical.
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State of the art Electron Microscopy can image atoms. An example is here...
http://www.sciencedaily.com/releases/2008/01/080122154357.htm
So, it is down to the size of a hydrogen atom.
But, not down to the size of a hydrogen nucleus.
But... getting close. Still, this says the hydrogen nucleus is 1.7 x 10-5Å
So, a couple of orders of magnitude smaller than the 0.5Å electron microscope above.
http://en.wikipedia.org/wiki/Hydrogen
http://upload.wikimedia.org/wikipedia/commons/4/4d/Hydrogen_atom.svg
20 years ago, I thought the limit was supposed to be "seeing" only really big (non-polymer) molecules.