Elastic Photon Scattering on Hydrogenic Atoms near Resonances

Andrey Volotka,Dmitrii Samoilenko,Stephan Fritzsche

doi:10.3390/atoms8020012

Abstract

Scattering of light on relativistic heavy ion beams is widely used for characterizing and tuning the properties of both the light and the ion beam. Its elastic component—Rayleigh scattering—is investigated in this work for photon energies close to certain electronic transitions because of its potential usage in the Gamma Factory initiative at CERN. The angle-differential cross-section, as well as the degree of polarization of the scattered light are investigated for the cases of 1 s − 2 p 1 / 2 and 1 s − 2 p 3 / 2 resonance transitions in H-like lead ions. In order to gauge the validity and uncertainty of frequently used approximations, we compare different methods. In particular, rigorous quantum electrodynamics calculations are compared with the resonant electric-dipole approximation evaluated within the relativistic and nonrelativistic formalisms. For better understanding of the origin of the approximation, the commonly used theoretical approach is explained here in detail. We find that in most cases, the nonrelativistic resonant electric-dipole approximation fails to describe the properties of the scattered light. At the same time, its relativistic variant agrees with the rigorous treatment within a level of 10% to 20%. These findings are essential for the design of an experimental setup exploiting the scattering process, as well as for the determination of the scattered light properties.

Highlights

Absorption and emission of a photon by an atom are the fundamental processes in atomic physics, which are of utmost importance for the characterization of the atomic system
The laser-induced fluorescence spectroscopy of atoms and molecules is based on an electronic excitation and subsequent fluorescence, which defines the electronic structure of a sample [1]
A proper description of the spectral properties involving the strongly bound electrons requires the incorporation of quantum electrodynamics (QED) effects [2]

Summary

Introduction

Absorption and emission of a photon by an atom are the fundamental processes in atomic physics, which are of utmost importance for the characterization of the atomic system. As the interest of atomic physics spreads to a higher energy domain, experimental findings reveal that in some cases, even relativistic consideration might not be enough. A proper description of the spectral properties involving the strongly bound electrons requires the incorporation of quantum electrodynamics (QED) effects [2]. Both relativistic and QED considerations can be, very tedious and demand from the researcher a background in the corresponding fields and sometimes considerable computational resources. The well-known and easy-to-use Bohr theory based method of the description of the electronic structure remains attractive in its simplicity

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Results

Conclusion