H.-L. Zhou

Photoionization of the Be isoelectronic sequence: total cross sections

The photoionization of the four-electron beryllium-like isoelectronic series from the neutral to Fe+22 has been studied for ground 1S and metastable 3P initial states. The wavefunctions of the final-state (target) ions were built using the CIV3 code. Both nonrelativistic LS-coupling R-matrix and relativistic Breit–Pauli (BP) R-matrix methods were used to calculate the cross sections in the photon-energy range between the first ionization threshold and the 1s24f7/2 threshold for each ion. Our total cross sections compare well with experiment which is available for Be, B+, C+2, N+3 and O+4. The agreement between the present work and previous calculations is discussed in detail. The importance of relativistic effects is seen by the comparison between the LS and the BP results.

Photoionization of Endohedrally Confined Ca (Ca@C60)

Photoionization cross section of endohedrally confined calcium is computed using R-matrix method.

Photoionization of potassiumlike transition-metal ions: Ti{sup 3+} to Fe{sup 7+}

Photoionization cross-section calculations are performed on potassiumlike transition metal ions (Ti{sup 3+}, V{sup 4+}, Cr{sup 5+}, Mn{sup 6+}, and Fe{sup 7+}) using both nonrelativistic (LS-coupling) and relativistic (Breit-Pauli) R-matrix methods for the ground ([Ne]3s{sup 2}3p{sup 6}3d {sup 2}D{sub 3/2}{sup e}) and the first excited ([Ne]3s{sup 2}3p{sup 6}3d {sup 2}D{sub 5/2}{sup e}) states of each of the five ions, along with the excited 4s {sup 2}S state of Ti{sup 3+}. Photon energies up to the first 3p ionization threshold are considered. The results show that for Ti{sup 3+}, the cross sections are dominated by the giant (3p{yields}3d) resonances which are analyzed and identified, while for the four other ions (V{sup 4+}, Cr{sup 5+}, Mn{sup 6+}, and Fe{sup 7+}), the 3p{yields}3d resonances lie below the ionization threshold, and the cross sections are dominated by 3p{sup 5}3dnd and 3p{sup 5}3dns Rydberg series of resonances. Comparison of the Ti{sup 3+} results with available theoretical and experimental data shows good agreement.

Satellite lines in the photoionization of ions; The Be isoelectronic sequence

Partial photoionization cross sections from the {sup 1}S ground and the {sup 3}P metastable states of the Be isoelectronic series to different final states, including a number of satellite (ionization plus excitation) channels are studied using the R-matrix method. As expected, the ratio of each satellite partial cross section to the dominant partial cross section is found to be a monotonic decreasing function of Z for both the ground and the metastable states. The complicated patterns of these ratios as functions of photon energy are analyzed.

Genetic-algorithm implementation of atomic potential reconstruction from differential electron scattering cross sections

We demonstrate the successful implementation of genetic algorithm for the retrieval of atomic potentials using elastic differential cross sections (DCSs) between free electrons and atomic ions for electron energies from a few to several tens of electron volts. Since the DCSs over this energy region can be extracted from laser-generated high-energy photoelectron momentum spectra, the results suggest that infrared lasers can be used to image the target structure. Extending to molecular targets, in particular, to transient molecules created by an earlier pump pulse, our results suggest that few-cycle infrared probe lasers can be used for dynamic chemical imaging with temporal resolution of a few femtoseconds.

Theoretical study of the photoionization of Be-like Ions

Photoionization cross sections from the ground and metastable states of Be-like ions have been calculated using the Breit-Pauli R-matrix method. The resonances were identified and characterized with energy levels, widths and effective quantum numbers using the QB program. The general behavior of the resonances was analyzed along the sequence. Relativistic effects are identified by comparing the Breit-Pauli result with our calculated LS R-matrix result.

Dynamical and relativistic effects in experimental and theoretical studies of inner-shell photoionization of sodium

High-resolution measurements for inner-shell photoionization of Na are presented along with Breit?Pauli R-matrix calculations. The results show excellent agreement, and give insight into the nature and importance of the various relativistic and correlation effects on the inner-shell process.

Dominance of hollow resonances in the photoionization of metastable 1s2s2p 4Po lithium

R-matrix calculations of the photoionization of the core-excited 1s2s2p 4Po state of atomic lithium have been performed. The cross section is shown to be dominated by hollow atom resonances, in contrast to valence-excited Li where these hollow resonances are small modulations of the background continuum cross section in the higher energy region.