Finally note that when the wavelength of the incoming light 
exceeds 
, there is always an outgoing photon carrying
a finite amount of energy 
. It is impossible for an electron
in free space to completely absorb the energy and momentum of a photon
and still satisfy the basic laws of the conservation of energy and
momentum. You will recall, however, that this complete absorption is
precisely what we assumed happened in our analysis of the
photoelectric effect. The resolution of this ``paradox'' is just to
observe that the electrons in the photoelectric effect are not free
but are inside of a crystal which can help absorb the momentum of the
incoming photons.