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Atom 'photographs'

  1. Jan 3, 2007 #1
    Hi. Well, I hope this doesn't get deleted because of speculative nature or anything, but this seems a good place to ask.
    I've read a lot of non-mathematical books on physics (sorry). I'm a very interested layman.

    I am curious about these pictures of atoms that you see. The ones that look like little ball bearings shrink wrapped in plastic. <grin>

    What, exactly are you seeing? In short, my understanding is that atoms and subatomic particles do not exist in any classical sense. (mathematical representations/probabilities and all that good stuff)

    I've read that there is a "grey" area (that has a name, but I've forgotten it) of where the transition of the quantum particles (the ghostly particles of probabilities) becomes the solid matter of everyday existance. Noone has yet to pinpoint this transition

    If that IS the case, just what it is we are seeing in those atom pictures?
    Are we seeing the actual atom or some sort of "collapsed probability wave' thingy that shows itself beyond this grey transition state (the name of which I can't recall) into our macrocosmic world

    pardon my ignorance ; )

  2. jcsd
  3. Jan 3, 2007 #2


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    There aren't really any such things as "atom pictures," in the sense of a normal photograph that you're familiar with in the macro world.

    If you could point us to some examples of the "atom picutres" you're looking at, we can tell you how to interpret them.

    - Warren
  4. Jan 3, 2007 #3


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    Not sure if this is going to help, but what you see in all those STM or AFM pictures is a pretty good approximation of the actual charge density (what physicists call the local density of states). The charge density at any point is itself just a number proportional to the square of the amplitude of the total wavefunction at that point.
    Last edited: Jan 3, 2007
  5. Jan 3, 2007 #4
    What you're probably seeing (electron orbitals) are pictures (though not produced with ordinary light) of where the electrons "are". That electron cloud basically determines everything of the atom, and the nucleus would be too small to draw anyway at that scale.
  6. Jan 3, 2007 #5

    Ok, thanks guys.
    I realize, of course that we aren't dealing with light. One of the pages this pic came from had a bit about STM. Lets see if I sorta get it.
    Basically what we have is a device for picking up concentrations of electric charge. A computer then takes that, color codes it and maps out a model based on these areas of concentrations. This colorized model can then be printed out.
    Sorta like making a 3d model of a terrain map then photgraphing that model to show people.

    So, I suppose that we are dealing in more modeling of "stuff" that are made up of fields and probabilities and whatnot and don't exist in a physical way.
  7. Jan 4, 2007 #6


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    These are STM images in which a very fine tip scans over a surface. In the crudest sense, you can make a current scan, or a voltage scan over the surface. Based on the variation of these values, you construct an "image" of the surface. So you are "seeing" these things via current or voltage.

    Now, the question of whether they "exist in a physical way" is too metaphysical. What you should ask is, is such in information or model be of any use? Sure it does. In solid state physics, we often model the ions that make up the crystal lattice as "solid sphere" as the first approximation. That allows us to make a very good estimate of the lattice constant and how these lattice ions are arranged in a material. Often, such a device is used to see if there are any inhomogeniety in the material, be in due to impurities, vacancies, or existence of different lattice domains. These are all important information regarding the properties of the material or the surface of the material.

  8. Jan 4, 2007 #7
    Thanks ZapperZ, I understand what you're saying.

    I would have liked to go into physics if I wasn't so grossly math challenged!
  9. Jan 4, 2007 #8
    The "grey area" between the macroscopic and microsscopic domains is sometimes called mesoscopic.
  10. Jan 11, 2012 #9
  11. Jan 11, 2012 #10

    Vanadium 50

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    This thread is 5 years old.
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