On the generalization of Nozieres—de Dominicis's theory for X-Ray absorption edges in metals to the case of finite temperature

A generalization of the Nozieres-de Dominicis theory of finite temperature for x-ray spectra at the absorption edge in metals is considered. The formalism of Green's time functions in the case of finite temperatures under the assumption that heat energy is small, is used. It is found that the temperature effect leads to broadening of the spectra lines in the shape of the Gaussian function.