Theoretical investigations on the dynamical correlation in double excitations of helium by the R -matrix method

The inner-valence excitations of a xenon 5s electron were investigated by the electron impact method with an electron-energy-loss spectrometer. The incident energies of the electron beam are varied between 500 eV, 100 eV, 50 eV and 30 eV in order to assign the resonances in the spectra. Besides the optically allowed excitations normally observed by photoabsorption methods, lots of optically forbidden transitions were studied in the present work. The autoionization Rydberg series 5s−1ns, 5s−1np, 5s−1nd have been observed. Their energy levels, resonant profiles and quantum defects were obtained from the electron-energy-loss spectra. Other than single excitations, there are many double excitations in this energy region, which needs further sophisticated calculations and higher resolution experiments to assign most of the resonant features.

Section: Introductionmentioning

confidence: 99%

Autoionization states in xenon investigated by electron impact

Yuan

Sakai

Umeda

et al. 2006

“…We can obtain the energy levels and wavefunctions as well as photoionization cross sections σ phi (hω) of interest. By fitting the photoionization cross section σ phi (hω) to Fano profiles [33,34],…”

Section: Theoretical Methodsmentioning

confidence: 99%

A theoretical study of dielectronic recombination processes of C²⁺ions in planetary nebulae

Peng¹,

Han²,

Wang³

et al. 2005

Self Cite

In the process of dielectronic recombination, an electron can be captured by a positive ion into doubly excited resonance states. These states can decay by autoionization or by radiative transitions which produce recombination lines. These lines are important to estimate the element abundances as well as the electron temperatures in planetary nebulae. The present paper reports a theoretical study by the R-matrix method for such processes of C2+ ions in planetary nebulae, which produce recombination lines λ5114 Å(4f′–3d′), λ4965 Å(3d′–3p′), λ4619 Å(4f′–3d′) and λ8794 Å(3d′–3p′). Our study is based on three sets of target orbitals, through which we elucidate the electron correlation and static polarization effects in the dielectronic recombination processes. The calculated energy level positions are used to indicate the degrees of our calculation convergence; especially those based on the set of target orbitals including the electron correlation and static polarization effects agree well with the experimental data within about 4%. For such recombination processes, the recommended radiative transition rates, autoionization rates and net recombination rate coefficients are also provided. We anticipate that the accuracy of our recommended recombination rate coefficients for the whole four dielectronic lines is about 7% within our theoretical model.

“…The preliminary experimental results (in arbitrary unit) are measured at 2.5 keV incident energy with 0.11 eV energy resolution. The experimental set-ups have been described in detail in the previous work [58,59]. For convenience of comparison, the experimental values are scaled so that the height of the peak for the [2p 5 ( 2 p o )3s 2 ( 1 S e )] 2 P state is nearly equal to the corresponding theoretical values.…”

Section: Resonance Transition: 2p 6 3s − 2p 5 3s3pmentioning

confidence: 99%

The generalized oscillator strengths for Na: monopole, dipole and quadrupole transitions

Han

Yan

et al. 2009

The generalized oscillator strengths (GOSs) of Na from the ground state [2p63s]32S excited to [2p6(n + 1)s](n + 1)2S, [2p6np]n2P, [2p6nd]n2D(3 ⩽ n ⩽ ∞) and adjacent continuum states are systematically investigated by the R-matrix method within the first Born approximation. The calculated energy levels of Na+ and Na are in good agreement with the experimental values. The energy dependence of the GOS extrema for the monopole, dipole and quadrupole transitions is investigated. The GOS density surfaces of 2S, 2P and 2D channels are calculated and their accuracies are tested rigorously by the available experiments as well as by the comparisons between the calculations on the different bases and the sum rule. With the surfaces tested, the high-energy electron impact excitation cross sections of the infinite Rydberg states near the threshold can be readily obtained by interpolations. In addition, the GOSDs for the resonance transitions 2p63s → 2p53s2 and 2p63s → 2p53s3p are investigated.