•The spacing between 2 levels in the
first atom must be twice the spacing between 2 levels in the second atom.
•
•The spacing between 2 levels in the
first atom must be half the spacing
between 2 levels in the second atom.
•
•The energy of the upper of 2 levels in
the first atom must be half that of the energy of the upper of 2 levels
in the second atom.