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Hydrogen excitation, ionisation and photon absorption

  1. Jul 10, 2014 #1
    I need help with something that i seemed to remember was fairly easy, but just can't seem to find the simple formula for:

    I have an amount of hydrogen atoms at a temperature of 10000 Kelvin. What percentage of them are ionised and what percentage of them are in the n=2 excited state.

    Secondly, where could i find the absorption cross section of a hydrogen atom in the n=2 state for the wavelength 656.28 nm? (aka Halpha line)
  2. jcsd
  3. Jul 10, 2014 #2


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    2017 Award

    Staff: Mentor

    That will depend on the density.

    See "Boltzmann factor".

    The NIST database could have that, not sure.
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