Determine the maximum wavelength of incident radiation that can be used to remove the remaining electron from a singly ionized helium atom He^{+} (Z = 2). Assume the electron is in its ground state.

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The Need for a Better Theory ... and its charge to be +2; α particles were simply nuclei of helium, _2^4 He. .... Let us assume that we know the wavelength to two significant digits, 5.0 X .... what is the energy, relative to the ionized atom, of the ground state, for which n = 1 ...

= 750 nm,

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