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Homework Help: Need a formula for Ionization HELP

  1. Feb 20, 2006 #1
    Need a formula for Ionization HELP!!

    What is the greatest wavelength of radiation that will ionize an unexcited Hydrogen atom?

    If someone could give me a fomula to work with I'd be EVER so greatful! I've been working on this for HOURS.
  2. jcsd
  3. Feb 21, 2006 #2


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    The longest wavelength corresponds to the lowest photon energy which would have to be at least equal to the ground state energy of a hydrogen atom. It's possible (I haven't checked) that longer wavelengths could accomplish this as a multiphoton process using intermediate excited states but those states usually have VERY short lifetimes.
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