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Heating Hydrogen in space

  1. Jun 6, 2013 #1
    How does one Photon heat one atom of Hydrogen? (One Proton, one Neutron, one Electron. If you'll allow)

    It looks to me that the solar energy (Photon) is captured by the field(s) between the Proton and the Neutron. It also looks to me that the Proton/Neutron field is complex and may capture ElectroMagnetic, ElectroStatic, and Gravatational energy. As the Hydrogen absorbs energy through its fields, the electron moves up in energy level. I believe we call that heating in chemestry.
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  3. Jun 6, 2013 #2


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    If you have a single isolated atom of hydrogen, I'm not sure it will absorb anything but the resonant frequencies of hydrogen. However, I'm more familar with relativity than QM.

    I'm vaguely aware that scattering effects do occur in bulk gasses (with more than one molecule - which is not an atom, to boot) but not really sure what the exact mechanism is. Since I don't really know the mechanism, I'm not positive that it requires more than one atom/molecule, though I suspect it might.

    This seems to me to belong in the QM forum, since you're specifying a single photon and a single atom, especialy. It doesn't have much to do with classical SR or GR.
  4. Jun 7, 2013 #3


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    Heat is a thermodynamic concept, so can only be applied to systems with a large number of components. You can't "heat" a single atom. You can, however, increase its kinetic energy.

    We talk so much about the excited atomic levels that we tend to forget that energy can be transferred between atoms and photons through elastic scattering as well. If you have a large number of atoms and a large number of photons, they will come to thermal equilibrium, and a hot photon gas will share its energy with the atoms simply by elastic collisions.
  5. Jun 7, 2013 #4


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    Thanks - that clarifies things for me a lot, I don't know about the OP. Another pair of questions, which are hopefully related enough not to derail the thread.

    Is it OK to say that if no excitation occurs (in the sense of excited atomic levels), we call the event "scattering" - but if excitation occurs, we call it absoprtion?

    Can we blur the distinction a bit by modeling a generic scattering event as a superposition of a non-interaction probability and an absoprtion and re-emission probability? I.e. can we always treat scattering as absorption and re-emission (and is it useful to do so) - or is this mostly done in popularized works?
  6. Jun 7, 2013 #5
    The most common isotope of hydrogen is just a proton and an electron, no neutron. But there is a form of hydrogen that has a proton, a neutron, and an electron, and even a (radioactive) form that has a proton and two neutrons, and an electron.
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