Rayleigh and Raman Scattering from Alkali Atoms

Abstract

Two computational methods developed recently [McNamara, Fursa, and Bray, Phys. Rev. A 98, 043435 (2018)] for calculating Rayleigh and Raman scattering cross sections for atomic hydrogen have been extended to quasi one-electron systems. A comprehensive set of cross sections have been obtained for the alkali atoms: lithium, sodium, potassium, rubidium, and cesium. These cross sections are accurate for incident photon energies above and below the ionization threshold, but they are limited to energies below the excitation threshold of core electrons. The effect of spin-orbit interaction, importance of accounting for core polarization, and convergence of the cross sections have been investigated.

A Fully Relativistic Approach to Photon Scattering and Photoionization of Alkali Atoms

“…Here, we will discuss a fully relativistic implementation of the principal value (PV) method which has previously been used to successfully calculate Rayleigh and Raman scattering on hydrogen and the alkali atoms as well as photoionization from the ground and excited states of hydrogen [31,32]. The relativistic extension of the PV method is virtually identical to the non-relativistic version; thus, we will only discuss the essential elements of the method and any changes from the non-relativistic implementation.…”

“…The detailed formalism we recently developed for photoionization, Rayleigh and Raman scattering on quasi one-electron atoms is discussed in [31,32]. Here, we present the details of its extension to the fully relativistic formalism.…”

“…where E t is the relativistic energy of the state |t , ω (ω ) andˆ (ˆ ) are the incident (scattered) photon energy and polarization, respectively [36]. The integrated Rayleigh or Raman cross section for scattering of unpolarized light from an initial state |i to a final state | f is given by [32]…”

“…Recently, we calculated Rayleigh and Raman scattering cross sections for the alkali atoms using a semi-relativistic model [32]. Here, we investigate relativistic effects on Rayleigh and Raman scattering cross sections using a fully relativistic model.…”

“…Recently, we have developed two computational methods for calculating photoionization, Rayleigh and Raman scattering cross sections for hydrogen-like atoms that are valid for incident photon energies above and below the ionization threshold [31,32]. The first method involves the direct numerical calculation of KHW matrix elements and utilizes principal value integration to deal with pole terms.…”