X-ray-photon scattering by an excited and ionized atom

Abstract

The scattering process of an x-ray photon by an excited and ionized many-electron atom with attosecond photon-electron contact interaction is theoretically investigated. The results of the authors' recent work [Hopersky et a l, Phys. Rev. A 88, 032704 (2013)] are generalized for the cases of (a) arbitrary energy of the photon that prepares the scattering state and (b) the scattering of the photon by the continuous spectrum electron of the ionization state of the atom. The atom of Ne is considered as the object of the study. Along with the effects of normal Compton and elastic scattering, the existence of anomalous inelastic scattering is predicted. It may be assumed that this effect will become a basis for an experimental method of increasing the energy of the photons generated, for example, by a free-electron x-ray laser. It is determined that during the elastic scattering of a photon by an electron of the continuous spectrum, along with the known contribution from the f Bessel function over the I = 0 harmonic (Thomson scattering), there is also a contribution from Bessel functions with harmonics / e [1; oo). The experimental discovery and application of the anomalous Compton photon scattering effect directly by the atomic electron of the continuous spectrum have their own practical interest.

Anomalous nonlinear X-ray Compton scattering

“…two types of processes leading to the same final state that differ in their intermediate states: an intermediate-state free electron ( Figure 5a) and an intermediate scattered photon (Figure 5b). Recently, Hopersky et al have considered theoretically resonant nonlinear sequential processes involving anomalous X-ray scattering from excited atoms where the first photon produces either a real excited atomic state (bound-bound) 32,33 or an excited ion (bound-free). 33 Our results suggest that, even far from resonance, the virtual processes corresponding to the diagrams shown in Figure 5 can be important.…”

X-ray-photon Compton scattering by a linear molecule

“…Finally, we note the following. Recent studies have theoretically predicted (for example, Be and Ne in the atomic phase) [51][52][53] and experimentally observed (for Be in the metallic phase) [54] a new but quite expected quantum effect, the effect of anomalous ( I 2 ω -photons (generated, for example, by x-ray free-electron lasers [54]) by a many-electron system. Generalization of those results to the case of a molecule is of both fundamental and practical interest, and is a subject of future investigation.…”