E. Luc-Koenig

Theoretical investigation on photoionization from Rydberg states of lithium, sodium and potassium

Cross sections for s, p and d have been computed in the framework of a single-electron model (non-relativistic) by using a parametric central potential. The evolution of the non-hydrogenic behaviour of photoionization cross sections near threshold is studied along Rydberg series; non-hydrogenic characters are particularly large for all the ns series and for the np series of K. The validity of the method is discussed and it appears that sigma sigma np and sigma nd values are more reliable than sigma ns. The results are compared to experimental data and other theoretical results, mainly provided by the quantum-defect theory. The agreement between the various results is generally very good for sigma np and sigma nd; the agreement is satisfactory even for the most unfavourable cases provided by sigma ns of Na and K.

Making ultracold molecules in a two-color pump-dump photoassociation scheme using chirped pulses

This theoretical paper investigates the formation of ground state molecules from ultracold cesium atoms in a two-color scheme. Following previous work on photoassociation with chirped picosecond pulses [Luc-Koenig et al., Phys. Rev. A, 70, 033414 (2004)], we investigate stabilization by a second (dump) pulse. By appropriately choosing the dump pulse parameters and time delay with respect to the photoassociation pulse, we show that a large number of deeply bound molecules are created in the ground triplet state. We discuss (i) broad-bandwidth dump pulses which maximize the probability to form molecules while creating a broad vibrational distribution as well as (ii) narrow-bandwidth pulses populating a single vibrational ground state level, bound by 113 cm{sup -1}. The use of chirped pulses makes the two-color scheme robust, simple, and efficient.

Electric-dipole transition probabilities of Al-like ions

Abstract Theoretical wavelengths, oscillator strengths, and transition probabilities for the E1-transitions between levels of the ground complex (n = 3)3 of the Al-like ions are presented. Calculations are made for 27 ions of the Al-sequence up to Z = 93. The Relativistic Parametric Potential Method was used to calculate energy levels and wave functions. All configuration interactions within the ground complex are included to account for electron correlations and intermediate coupling. Relativistic effects are taken into account by means of the Coulomb-Dirac Hamiltonian. The Breit term and the Lamb shift are neglected.

Optimizing the photoassociation of cold atoms by use of chirped laser pulses

Abstract.Photoassociation of ultracold atoms induced by chirped picosecond pulses is analyzed in a non-perturbative treatment by following the wavepacket dynamics on the ground and excited surfaces. The initial state is described by a Boltzmann distribution of stationary continuum states. The chosen example is photoassociation of cesium atoms at temperature

Identification of Highly-Ionized Xenon Spectra (Xe XXVI Through XXXI) Excited in the Plasma of the TFR Tokamak

T = 54 \mu

Systematic theoretical study of the Stark spectrum of atomic hydrogen. I. Density of continuum states

K from the

Systematic trends of the relativistic energy levels and oscillator strengths for electric dipole transitions within the ground complex of aluminium-like ions

a^3 \Sigma_u^ + (6s,6s)

Relativistic effects on transition probabilities 3P1→1S0 for group II elements

continuum to bound levels in the external well of the 0g-(6s + 6p3/2) potential. We study how the modification of the pulse characteristics (carrier frequency, duration, linear chirp rate and intensity) can enhance the number of photoassociated molecules and suggest ways of optimizing the production of stable molecules.

Threshold effects in the photoassociation of cold atoms: R−6 model in the Milne formalism

The spectrum of xenon injected into the TFR tokamak plasma has been recorded in the range 10-90 A by means of a 2 m grazing incidence spectrograph. Forty-four lines and unresolved transition arrays pertaining to multicharged xenon ions isoelectronic with Cu I, Ni I, Co I, Fe I, Mn I and Cr I have been identified by means of various theoretical methods. The 17 observed lines of the 3p63d8-3p53d9 transition array, have allowed the wavelengths of the magnetic dipole transitions occurring within the ground configuration 3d8 of Xe XXIX to be predicted.

Eigenchannel R-matrix study of two-photon processes including above-threshold ionization in magnesium

An exact method which allows the authors to obtain normalised wavefunctions for a hydrogen-like atom in the presence of a uniform electric field is reported. An unambiguous classification of the Stark states is presented which correlates a given Stark state to a unique zero-field state; this classification is valid for any Stark states-resonant or non-resonant-and at any energy smaller or greater than E0 the ionisation limit of the unperturbed atom. From the supersymmetry in the hydrogen spectrum, states with different values for m, the magnetic quantum number, or for n1, the generalised parabolic quantum number, can be considered independently. A parabolic critical energy can be defined for any state m, n1; for sufficiently high value of n1 the critical energy is greater than E0. A systematic study of the positions and widths of the resonance in a broad energy range below E0 is presented.