H. Le Rouzo

Partial photoionization cross section and photoelectron angular distribution for the X 2Σg+ state of N2+ in the static‐exchange approximation

The partial photoionization cross section of N2 leading to the production of N2+ in its X 2Σg+ ground state is calculated in the single‐center frozen core static‐exchange approximation. The initial and final states are antisymmetrized products using SCF molecular orbitals of either N2 or N2+ ground states. All these calculations reproduce well the σu shape resonance in the partial cross section. The photoelectron angular distribution is also calculated and the average over the vibrational motion is performed. The R‐averaged results are in agreement with recent measurements using synchrotron radiation. The branching ratio of the cross sections leading N2+ in its two lowest vibrational states compares rather well with the experimental values obtained recently by West et al.

Ab initio approach to the multichannel quantum defect calculation of the electronic autoionisation in the Hopfield series of N2

The two-step formulation of the multichannel quantum defect theory, applied to molecular electronic autoionistion by Giusti-Suzor (1980) and Lefebvre-Brion (1973) is used to calculate the total and partial photoionisation cross sections in the region of the Hopfield series on N2, the 700-730 AA wavelength range. The electronic quantities necessary for this treatment are obtained from ab initio calculations. The cross sections and the photoelectron angular distribution parameters are in satisfying agreement with experiment. The results clearly show that the absorption series correspond to the (B2 Sigma u+)nd sigma g series and the apparent emission series to the (B2 Sigma u+)nd pi g series.

Theoretical study of shape resonances in the partial photoionization cross sections for the b 4Σg− and B 2Σg− states of O2+

Using the single‐center static‐exchange approximation, the 3σg photoionization cross section of O2 is calculated. The R‐averaged results are obtained for the production of O+2 in the b 4Σ−g and B 2Σ−g states. Shape resonances, a few electron volts wide, are found at 3 and 2.5 eV from the threshold for these two states, respectively. We find reasonable agreement with the experimental cross sections for the B 2Σ−g state and with the β values for the b 4Σ−g state. For this last state, comparison between theory and experiment leads us to a possible interpretation of the data, but a definite answer can not be given without taking into account the autoionized Rydberg states.

Theoretical approach to the Cooper minimum in hydrogen iodide

Abstract Calculations of the photoionization cross section corresponding to the X 2 Π (5pπ) −1 ion state and of the angular asymmetry parameter β are performed for the HI molecule in the 10.4–92 eV range. Within the frozen-core static exchange approximation, no Cooper minimum is found in the cross section, contrary to experiment. Interchannel coupling with the continuum states corresponding to ion states associated with a 4d hole is also partially taken into account. Two energy points are calculated within this coupling scheme, showing better agreement with experiment, especially for β at high energies.

Exact double-continuum solution of a correlated atomic model

The dynamics of double ionization is of considerable interest as being a striking manifestation of the electron correlation. This is an essentially nonseparable problem for which it is highly desirable to have an analytically soluble model for reference. In this paper, the correlated double-continuum solution of a two-particle atomic model is obtained in closed form. Although particles are one-dimensional and potentials are of -type, this model provides for double photoionization of helium, energy distributions of ejected electrons and total cross sections in qualitative agreement with those of more realistic calculations.