Mau Hsiung Chen

Relativistic radiationless transition probabilities for atomic K- and L-shells☆

Abstract : Auger and Coster-Kronig transition probabilities have been calculated ab initio relativistically from perturbation theory, for frozen orbitals, in teh Dirac-Hartree-Slater approach. Results in the j-j coupling scheme are tabulated for or = 22 elements with atomic numbers 18 or = Z or = 96.

Theoretical L-shell Coster-Kronig energies 11 ≤ Z ≤ 103

Abstract Relativistic relaxed-orbital calculations of L -shell Coster-Kronig transition energies have been performed ab initio for all possible transitions in atoms with atomic numbers 11 ≤ Z ≤ 103. Hartree-Fock-Slater wavefunctions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first-order approximation to the local approximation was thus included. Quantum-electrodynamic corrections were made. Each transition energy was computed as the difference between results of separate self-consistent-field calculations for the initial, singly ionized state and the final two-hole state. The following quantities are listed: total transition energy, “electric” (Dirac-Hartree-Fock-Slater) contribution, magnetic and retardation contributions, and contributions due to vacuum polarization and self energy.

Theoretical atomic inner-shell energy levels, 70 ≤ Z ≤ 106

Abstract Theoretical 1s, 2s, 2p 1 2 , and 2p 3 2 energy levels in neutral atoms with 70 ≤ Z ≤ 106 are listed. The computations are relativistic and include complete relaxation. The electric energies are based on Dirac-Hartree-Slater wave functions; a first-order correction to the local approximation is made. The Breit-interaction energy and vacuum-polarization energy are listed separately, and a self-energy correction is included. These calculations differ from earlier work by the authors in that a more accurate, frequency-dependent expression for the Breit energy is employed, a Fermi (rather than uniform) distribution of the nuclear charge is assumed, and a screened self-energy correction is applied to the 1s, 2s, 2p 1 2 , and 2p 3 2 levels. Comparison of results with 1967 experimental values adopted by Bearden and new work of Borchert shows better agreement than is provided by earlier calculations with frequency-independent Breit interaction and a uniform nuclear charge distribution.

L x-ray satellite energies

Abstract Theoretical energies are tabulated for the L x-ray satellites that arise from electric dipole and quadrupole transitions in the presence of one spectator hole in the M- or N-shell. Results are listed for 11 elements with atomic numbers 65 ≤ Z ≤ 95. The computations are relativistic and include quantum-electrodynamic corrections. Subsidiary tables list the Coulomb and Breit interaction energies for double-hole states and the relative x-ray intensities of double-hole multiplet states.

Quasi-atomic L-MM Auger spectra of solid Cu and Zn

Abstract Experimental L 3 -M 4,5 M 4,5 Auger spectra of metallic Cu and Zn show distinct characteristics of free-atom spectra but do not reflect the band structure. This quasi-atomic phenomenon in solids is tentatively explained as electron localization due to increased screening.

Atomic inner-shell transitions

Atomic inner-shell processes have quite different characteristics, in several important aspects, from processes in the optical regime. Energies are large, e.g., the 1s binding energy reaches 100 keV at Z = 87; relativistic and quantum-electrodynamic effects therefore are strong. Radiationless transitions vastly dominate over photon emission in most cases. Isolated inner-shell vacancies have pronounced single-particle character, with correlations generally contributing only ~1 eV to the 1s and 2p binding energies; the structure of such systems is thus well tractable by independent-particle self-consistent-field atomic models. For systems containing multiple deep inner-shell vacancies, or for highly stripped ions, the importance of relativistic intermediate coupling and configuration interaction becomes pronounced. Cancellation of the Coulomb interaction can lead to strong manifestations of the Breit interaction in such phenomena as multiplet splitting and hypersatellite x-ray shifts. Unique opportunities arise for the test of theory.

Atomic Inner‐Shell Threshold Excitation with Synchrotron Radiation

Monochromatized synchrotron radiation from a focused 8‐pole wiggler beam line has been used to excite the L2 and L3 holes of atomic Xe and the K hole of atomic Ar near their photoionization thresholds. We have measured the Xe L3‐M4M5 lpar;1G4rpar; Auger line, the Xe L2−L3N45 Coster‐Kronig line, and the Ar K−L23L23 Auger line with incident x‐ray energies from ∼20 eV below threshold to ∼200 eV above threshold. The spectra allow accurate determination of spectator‐ satellite energy shifts, postvcollision interaction (PCI) shifts in the diagram‐line energy, and spectral changes associated with the resonant Raman Auger (RRA) effect. The energies of satellites corresponding to photoelectrons promoted to bound states exhibit linear dispersion as a function of the initial photon energy. The measured post‐collision interaction energy shifts of the diagram lines agree qualitatively with semiclassical PCI theory above threshold. In all cases, the energy of the diagram line is observed to decrease below threshold. Th...