Li Jia-Ming

IONIZATION CHANNELS OF SUPEREXCITED MOLECULES

Infinite perturbed Rydberg states for molecules can be correlated with quantum defect parameters. We present our theoretical results of Rydberg series (ionization channels) for the NO molecules. In the fσ channel, there exists a resonance which leads to the fine structure near the x-ray absorption K edges. The resonance energy decreases as the internuclear distance increases. Such relation can be utilized to diagnose the relevant bond-length of the molecules chemisorbed on the surface.

Fine-structure of excited atomic ions along potassium isoelectronic sequence

To perform theoretical calculations of electronic structures of high Z atomic ions, one has to consider the configuration mixings due to excitations and rearrangements of the core and valence electron orbitals with the same principal quantum number. We present a method to examine systematically such configuration mixings along isoelectronic sequences. As an illustrative example, such configuration mixings give rise to a reversed fine-structure splitting of 4 2F5/2,7/2 states for atomic ions with Z ≈ 36 along the potassium isoelectronic sequence; while the 5F, 6F, and 7F have normal fine-structure splittings.

Relativistic Multichannel Theory: Theoretical Studies of Excited Energy Structure of Ar Atom

We here present a relativistic multichannel theory which can be regarded as an extension of traditional configuration interaction theories by including continuum configuration interactions. Our relativistic multichannel theory aims directly to calculate the compact set of physical parameters (μα,Uiα) in multichannel quantum defect theory. Taking Ar atom as an example, we compare our calculated orbital energies with traditional configuration interaction calculations as well as experimental measurements.

Relativistic Theoretical Calculation of O III: Radiative Transition Rates and the Bowen Mechanism in Planetary Nebulae

A full relativistic configuration interaction (RCI) calculation of transition energies and radiative transition rates involved in O III Bowen fluorescence mechanism is presented. The calculated ratios of transition line intensities are in good agreement with the observed ratios. The discrepancies between the RCI calculation and prediction based on LS coupling scheme show that a delicate balance between the electron correlations and the spin-orbital interactions should be important even for the low-Z O III ion.

Quantum Defect Theory: Rydberg States of the NO Molecules

The NO molecule in Rydberg states consists of a closed shell molecular ion and an excited electron in a Rydberg molecular orbital. It is a comparatively simple but non-trivial excited molecule. Here, we present our theoretical calculation of the quantum defects of these Rydberg states. The theoretical results are in good agreement with the experimental data.

Theoretical Calculation of Dielectronic-Recombination Cross Section for Hydrogen-Like Argon

Dielectronic-recombination cross sections of hydrogen-like argon are calculated conveniently by our simplified relativistic configuration-interaction method. The results for the KLL, KLM, KLN, and KLO resonances are in good agreement with experimental measurement within a few percent. Our methods can provide various dielectronic-recombination rates which can satisfy the need for relevant applications.

Electronic Structure of Molecular Rydberg States

Comprehensive theoretical results of the molecular Rydberg structures with the total-electron numbers starting from 2 to 18 are reported. We attempt to elucidate: (1) systematic trends of the variation of the eigen quantum defects among those molecules, (2) characteristics of the molecular dynamics between the excited electron and the corresponding molecular ions.

Absolute measurement of photoionization cross-sections of excited states 3s5s1S and 3s4d1D in magnesium

We report the first experimental investigation of the photoionization cross-sections of singlet excited states 3s5s1S and 3s4d1D in atomic magnesium, which can not be directly reached from the ground state. The measured absolute values are σ3s5s1S (571.1nm)=(0.27 ± 0.09)Mb and σ3s4d1D (552.8nm)=(2.6 ± 0.9)Mb. Theoretical calculations were given, which are in good agreement with the measured values.

Electron Impact Excitation Cross Section and Rate: Revised Bethe Formula

Based on Born approximation, we introduce a revised Bethe formula to calculate the excitation cross sections and rates conveniently for multi-electron atoms, whose generalized oscillator strength may have nodes and/or peaks. With the quasi-universal correction function, it can also be extended to low energy region.

Theoretical Calculation of Differential Cross Section for e+-Ar and e--Ar Elastic Scattering

The differential cross sections for e--Ar and e+-Ar elastic scattering are calculated by relativistic partial wave expansion method. In the processes an incident particle (electron or positron) is treated as moving relativistically in an effective central potential. For electron-atom scattering, the effective potential is calculated by relativistic self-consistent-field (SCF) method with the Slater local exchange approximation. For the positron scattering, the effective potential is the electrostatic potential determined by the ground-state electron charge density calculated by the SCF method. For atomic target polarization due to the incident charge particle(electron or positron), the effect is treated approximately by adding a static polarization potential to the SCF potentials. The calculated results show that the polarization effect is very important for the low energy positron-atom scattering.