ABSTRACT
In models based on the Onsager theory, it is generally assumed that the excess energy of excitation is dissipated during the initial motion of a hot electron. For a given transition, this leads to the prediction that the thermalization distance should increase with increasing excitation energy, since an electron with higher initial
energy will require a longer thermalization distance to dissipate its excess energy (Knights and Davis, 1974). Such a wavelength dependence, however, is not observed in many materials. In 1979, Noolandi and Hong argued that this excess energy was largely dissipated by internal conversion with a resulting thermaliza tion distance that was very small, at most a few molecular distances. Figure 6 represents the conventional Onsager model. Figure 7 illustrates the process proposed by Noolandi and Hong where the electron thermalizes by internal conversion with a very short thermalization distance. For the latter, Noolandi and Hong argue that the appropriate boundary condition is a partly absorbing sphere of
finite radius at the origin, in contrast to a perfectly absorbing sphere of vanishing radius as used by Onsager.
