•First rigorous theoretical treatment is done for electron impact ionization of Se3+.•Dominant processes are elucidated for electron impact ionization of Se3+.•The population fractions are diagnosed ...for a recent experiment.
Electron impact single ionization cross sections are theoretically investigated from the ionization threshold to 1000eV for the levels belonging to the ground and two lowest excited configurations of (Ni)4s24p, 4s4p2, and 4s24d of Se3+ using a detailed level-to-level distorted-wave formalism. The ionization cross sections of the two levels belonging to the configuration of 4s24p are nearly equivalent and so are 4s24d, whereas large difference is found for the eight levels of 4s4p2. The theoretical results are utilized to analyze and interpret a recent experimental measurement for the single-ionization cross section of Se3+ (Alna’washi et al., 2014). The population distributions existed in this experiment are deduced. Except for the levels of the ground configuration, there exist populations from levels of the excited configuration of 4s24d.
Photoionization cross sections for the excited states belonging to configurations of 1s22s2pm(m 5−2) of Neon ions are calculated in the region of double K-vacancy resonances in a close-coupling ...approximation. Autoionization widths of the double K-vacancy states are obtained from the cross sections by fitting a Fano profile.
The ionic and electronic structures of warm dense silane at the densities of 1.795, 2.260, 3.382, and 3.844 g/cm(3) have been studied with temperatures from 1000 K to 3 eV using quantum molecular ...dynamics simulations. At all densities, the structures are melted above 1000 K. The matter states are characterized as polymeric from 1000 to 4000 K and become dense plasma states with further increasing temperature to 1 eV. At two lower densities of 1.795 and 2.260 g/cm(3), silane first dissociates and then becomes the polymeric state via a chain state from the initial crystalline structure. At higher densities, however, no dissociation stage was found. These findings can help us understand how the warm dense matter forms. A rise is found for the direct current electric conductivity at T ∼ 1000 K, indicating the nonmetal-to-metal transition. The conductivity decreases slightly with the increase of temperature, which is due to the more disordered structures at higher temperatures.
The internal solar structure predicted by the standard solar model disagrees with the helioseismic observations even by utilizing the most updated physical inputs, such as the opacity and element ...abundances. By increasing the Rosseland mean, the decade-old open problem of the missing opacity can be resolved. Herein, we propose that the continuum electrons in the radiative processes lose phases and coherence as matter waves, giving rise to a phenomenon of transient spatial localization. It not only enhances the continuum opacity but also increases the line widths of the bound-bound transitions. We demonstrate our theoretical formulation by investigating the opacity of solar mixtures in the interior. The Rosseland mean demonstrates an increase of 10%–26% in the range of 0.3
R
⊙
–0.75
R
⊙
. The results are compared with the recent experimental data and the existing theoretical models. Our findings provide novel clues to the open problem of the missing opacity in the solar interior and new insight on the radiative opacity in the hot dense-plasma regime.
Electron impact collision strengths among 560 levels of Si IX, 320 levels of Si X, and 350 levels of Si XI have been calculated using the Flexible Atomic Code of Gu M.F. Gu, Astrophys. J. 582 (2003) ...1241. Collision strengths
Ω at 10 scattered electron energies, namely 10, 50, 100, 200, 400, 600, 800, 1000, 1500, and 2000
eV, are reported. Assuming a Maxwellian energy distribution, effective collision strengths
ϒ are obtained on a finer electron temperature grid of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0
MK, which covers the typical temperature range of astrophysical hot plasmas. Additionally, radiative rates
A and weighted oscillator strengths
gf are given for the more probable transitions among these levels. Comparisons of our results with available predictions reported in earlier literature are made and the accuracy of the data is assessed. Most transitions exhibit a good agreement, but large differences in
gf appear for a few cases, which are due to the different configuration interactions included in different theoretical calculations. For excitations among levels of the ground and lower excited configurations, large discrepancies of
ϒ may have resulted from the consideration of resonance effects in earlier works.
Electron impact excitation of Ca-like iron Fe6 Zeng, Jiaolong; Liang, G. Y.; Zhao, G. ...
Monthly notices of the Royal Astronomical Society,
02/2005, Letnik:
357, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Electron impact collision strengths, energy levels, oscillator strengths and spontaneous radiative decay rates are calculated for Fevii using the Flexible Atomic Code. The configuration interactions ...included in the calculations of atomic structure and excitation are among the configurations of (Ne)3s23px3dy (x+y= 8, x= 6 − 3), 3s23p63dnl (n= 4, 5, l= 0, 1, …, n− 1), 3s23p64l4l′ (l, l′= 0, 1, 2, 3), 3s3px3dy (x+y= 9, x= 6, 5) and 3s23p53d24s. Collision strengths are calculated at 20 scattered electron energies (5–6000 eV) for the energetically lowest 340 levels, with the highest excited states corresponding to levels belonging to the configuration of 3s23p63d5g. Effective collision strengths are obtained by assuming a Maxwellian electron velocity distribution at 15 temperatures from 10 to 500 eV. Comparison has been made with earlier theoretical collision strengths for the transitions within the ground configuration 3s23p63d2, which are the only data available in the literature. Illustrative examples are given for some strong transitions belonging to the arrays of 3s23p63d2–3s23p53d3, 3s23p63d4p and 3s23p63d4f. The results show that the oscillator strengths and collision strengths are very sensitive to the configuration interaction. The complete data set is available electronically from .
The L-shell radiative opacity of lowly charged Cu plasmas is investigated using a detailed level accounting method. The transmission spectra are compared with a recent experiment at ∼16 eV and 0.005 ...g/cm3, and good agreement is observed. For a systematic study, radiative opacities caused by 2p → 3d transitions at temperatures of 10–35 eV and densities of 0.001–0.1 g/cm3 are calculated. The dominant ionization stages are lowly charged ones with an open M-shell at such plasma conditions. The result shows that charge state distribution and radiative opacities are very sensitive to temperature. The two strongest absorption peaks of 2p3/2 → 3d5/2 and 2p1/2 → 3d3/2 caused by relativistic orbital splitting are well separated at temperatures lower than 25 eV, whereas they are mixed together to form a broadband structure at higher temperatures.
Nuclear dynamics in dense hydrogen, which is determined by the key physics of large-angle scattering or many-body collisions between particles, is crucial for the dynamics of planet's evolution and ...hydrodynamical processes in inertial confinement confusion. Here, using improved ab initio path-integral molecular dynamics simulations, we investigated the nuclear quantum dynamics regarding transport behaviors of dense hydrogen up to the temperatures of 1 eV. With the inclusion of nuclear quantum effects (NQEs), the ionic diffusions are largely higher than the classical treatment by the magnitude from 20% to 146% as the temperature is decreased from 1 eV to 0.3 eV at 10 g/cm(3), meanwhile, electrical and thermal conductivities are significantly lowered. In particular, the ionic diffusion is found much larger than that without NQEs even when both the ionic distributions are the same at 1 eV. The significant quantum delocalization of ions introduces remarkably different scattering cross section between protons compared with classical particle treatments, which explains the large difference of transport properties induced by NQEs. The Stokes-Einstein relation, Wiedemann-Franz law, and isotope effects are re-examined, showing different behaviors in nuclear quantum dynamics.
Calculation details of radiative opacity for lowly ionized gold plasmas by using our developed fully relativistic detailed level-accounting approach are presented to show the importance of accurate ...atomic data for a quantitative reproduction of the experimental observations. Even though a huge number of transition lines are involved in the radiative absorption of high- Z plasmas so that one believes that statistical models can often give a reasonable description of their opacities, we first show in detail that an adequate treatment of physical effects, in particular the configuration interaction (including the core-valence electron correlation), is essential to produce atomic data of bound-bound and bound-free processes for gold plasmas, which are accurate enough to correctly explain the relative intensity of two strong absorption peaks experimentally observed located near photon energy of 70 and 80 eV. A detailed study is also carried out for gold plasmas of an average ionization degree sequence of 10, for both spectrally resolved opacities and Rosseland and Planck means. For comparison, results obtained by using an average atom model are also given to show that even for a relatively higher density of matter, correlation effects are also important to predict the correct positions of absorption peaks of transition arrays.
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