Vacuum energy extraction photons

The energy required to extract an electron, i.e., the ionization potential Ip, for the majority of complex molecules has values from 7 to 12 e.v. and above. This corresponds to photons in the vacuum ultraviolet range (1800-1000 A.). 

The energy required to extract an electron from the organic solid to a point in vacuum outside its surface, i.e., the work function

maximum kinetic energy as function of the photon energy. The remarkable constancy of the work function, which is independent of the photon energy, leads to the following conclusions (1) the probability of the electron abstraction from the solid does not vary with the photon energy ... 

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