Rayleigh scattering from excited states of atoms and ions

Abstract

Elastic photon scattering from the ground state and various excited states of carbon atoms and ions has been investigated, using the S-matrix formalism, for incident photon energies ranging from 100 eV to 10 keV, contrasting the results obtained for different configurations. The excited states considered include hollow-atom states, where one or more inner shells are completely vacated. Ionic cases are considered as a limit of excitation. Results demonstrate how cross sections for different excited states group together according to shared properties of the configurations, such as the number of K electrons. Cross sections may exhibit deep dips below the K edge, depending on the occupation of the subshells corresponding to the strongest transitions. Scattering from excited states can have significantly larger cross sections than scattering from the ground state, particularly just below the K resonance region, and therefore it needs to be considered in situations where there is a large population of these excited states. Results are interpreted in terms of form-factor arguments and the qualitative behavior of individual subshell amplitudes. The angular dependence of cross sections can be understood in terms of angle-dependent form factors and anomalous scattering factors, taken to be angle independent. Cases are identified for which excited-state total integrated cross sections are much larger than the corresponding cross sections for scattering from the ground state. Our main results use an averaging over magnetic substates at the level of the amplitude, exact only for fully filled subshells, but generally appropriate for the carbon case considered, which simplifies the discussion and explains most of the general features. We also present results for a hollow lithium atom with and without this approximation to illustrate the differences that can arise in certain circumstances.

Near-edge anomalous Rayleigh scattering in Cu ions

“…These results confirm predictions from the independent particle approximation (IPA), in particular the oscillatory nature of below edge structure due to bound-bound (b-b) resonant intermediates and increases in the size of b-b resonances with decreasing Z (Carney et al, 2000) underlining potential application to the study of the low-Z electrolytes in biological systems.…”

Coherent scattering and macroscopic coherence: implications for neutrino, dark matter and axion detection

“…As a result, the ω 4 suppression would still be present. This is quite analogous to the situation with photon scattering on atomic systems, where the scattering on charged ions exhibits at ω ≪ ωat the same ω 4 suppression as the scattering on neutral atoms [34,35].…”

Tutorial on fundamentals of radiation physics:

“…Cross sections approach a common high-energy limit along one of three curves according to the number of 1 s electrons. FromCarney et al (2000a).…”