PHOTOEXCITATION BY X-RAYS IN ENERGY BANDS OF SOLIDS

The general formalism of the photoexcitation in the energy bands of solids is first very shortly reviewed. Approximations based on the relatively high photon energy are developed, and the energy distribution of the excited electrons is calculated in the free electron model. Taking into account the conservation of the wave vectors, the result shows that the photoexcitation does not produce any serious selection in the reciprocal space. Thus, if the matrix elements for the transitions are constant, the energy distribution of the excited electrons is proportional to the density of the occupied states. A qualitative discussion shows that this result holds for a more realistic description of the electron states than the free electron model. © 1969 Springer-Verlag.