The author presents original results on the dynamics of two-electron processes in impurity semiconductors using the Mössbauer spectroscopy method in crystalline and vitreous chalcogenides of lead (PbS PbSe PbTe) germanium (Ge – S Ge –Se) and arsenic (As – S As – Se As – Te). The book is addressed to researchers doctoral students and graduate students specializing in the physics of semiconductors.