R-matrix calculation of Raman couplings and dynamical Stark shifts in heavy alkaline-earth atoms
Laboratoire Aimé Cotton, CNRS II, Bâtiment 505, 91405 Orsay Cedex, France
2 Atomic and Molecular Physics Laboratory, Physics Department, University of Ioannina, 45110 Ioannina, Greece
Published online: 15 December 1999
We report a theoretical approach based on a combination of jj-coupled eigenchannel R-matrix and multichannel quantum-defect (MQDT) methods suitable to determine Raman couplings, dynamical Stark shifts and threshold-resolved ionization rates in heavy alkaline-earth atoms. These atomic parameters are needed to analyze the partial photoelectron spectra and the ionization dynamics of multiphoton processes in a perturbative treatment of the field-atom interaction to the lowest non-vanishing order of perturbation theory. Numerical results are presented in barium, pertaining to the experimental level scheme used by Wang, Chen and Elliott [Phys. Rev. Lett. 77, 2416 (1996)] to study coherent control through two-color interfering paths. Particular emphasis is given on the comparison of length and velocity formulations for the electric dipole operator.
PACS: 31.15.Ar – Ab initio calculations / 32.80.Fb – Photoionization of atoms and ions / 32.80.Qk – Coherent control of atomic interactions with photons
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999