Classical recombination cross section

Classical theory is used to calculate the recombination cross section of electrons in the field of an attractive Coulomb center. The cross section differs from the one calculated in accordance with Kramers's well-known expressions, which also has a semiclassical nature. It is shown that the results of the classical calculation and Kramers's formulas describe different cases. The classical recombination cross section applies for low initial velocities of the electrons, when emission of soft photons results in capture.