Structures in low-energy classical bremsstrahlung

We study classical bremsstrahlung from neutral atoms and investigate the origins of the structures in the energy dependence of the differential cross section ωdσ/dω and the asymmetry parameter a2, using soft-photon limit results in terms of elastic scattering. We show that trapping features in elastic scattering do not contribute to the structures. Rather, these structures result from the suppression of contributions to the radiation from certain angular momenta at certain energies. This corresponds to the association of structures in quantum bremsstrahlung with zeros in certain angular momentum matrix elements at certain energies. (author)