Fowler's Hypothesis and the Determination of Photoemission Thresholds

It is shown that Fowler's hypothesis to explain photoemission from metals is not necessary to obtain a spectral dependence of quantum yield near threshold that varies as $Y^{\frac{1}{2}}\propto (h\nu -e\phi )$. It is not possible to distinguish between a Fowler distribution and an isotropic distribution of excited electrons even if rather extreme cases of electron scattering are included. As a result, knowledge that photoemission from a metal follows a Fowler plot does not permit any inferences regarding the nature of the initial excitation.