Related papers: Photoionization and Opacity
Using the eigenchannel R-matrix method we calculate partial photoionization cross sections from the ground state of the helium atom for incident photon energies up to the N=9 manifold. The wide energy range covered by our calculations…
Using the new version of the photoionization code Titan designed for plane-parallel photoionized thick hot media, which is unprecedented from the point of view of line transfer, we have undertaken a study of the influence of different…
A comprehensive study of high-accuracy photoionization cross sections is carried out using the relativistic Breit-Pauli R-matrix (BPRM) method for (hnu + Fe XVII --> Fe XVIII + e). Owing to its importance in high-temperature plasmas the…
Radiative cooling is central to a wide range of astrophysical problems. Despite its importance, cooling rates are generally computed using very restrictive assumptions, such as collisional ionization equilibrium and solar relative…
A theoretical investigation of photoabsorption and photoionization of Fe^{14+} extending beyond an earlier frame transformation R-matrix implementation is performed using a fully-correlated, Breit-Pauli R-matrix formulation including both…
Recent experimental work on the photorecombination and the photoionization of astrophysically relevant atomic ions employing the merged-beams technique at heavy-ion storage-rings and synchrotron-light sources, respectively, is summarized.…
We describe an ab initio and non-perturbative $R$-matrix with time-dependence theory for ultrafast atomic processes in light fields of arbitrary polarization. The theory is applicable to complex, multielectron atoms and atomic ions subject…
A new opacity model based on the Super-Transition-Array (STA) method for the calculation of monochromatic opacities of local thermodynamic equilibrium plasmas, was developed. The atomic code, named STAR (STA-Revised), is described and used…
The IRON Project, initiated in 1991, aims at two main objectives, i) study the characteristics of and calculate large-scale high accuracy data for atomic radiative and collisional processes, and ii) application in solving astrophysical…
We present R-Matrix with time dependence (RMT) calculations for the photoionization of helium irradiated by an EUV laser pulse and an overlapping IR pulse with an emphasis on the anisotropy parameters of the sidebands generated by the…
We present $R$-matrix calculations of photoabsorption and photoionization cross sections across the K-edge of Mg, Si, S, Ar, and Ca ions with more than 10 electrons. The calculations include the effects of radiative and Auger damping by…
Material ejected during (or immediately following) the merger of two neutron stars may assemble into heavy elements by the r-process. The subsequent radioactive decay of the nuclei can power electromagnetic emission similar to, but…
Photoionization of an atom in the presence of a neighboring atom of different species is studied. The latter first undergoes resonant photoexcitation, leading to an autoionizing state of the diatomic system. Afterwards, the excitation…
Theoretically self-consistent calculations for photoionization and (e + ion) recombination are described. An identical eigenfunction expansion for the ion is employed in coupled channel calculations for both processes, thus ensuring…
Aimed at solving the outstanding problem of solar opacity, and radiation transport plasma models in general, we report substantial photoabsorption in the high-energy regime due to atomic core photo-excitations not heretofore considered. In…
The relations between photoionization cross sections and photon radius are obtained on basis of quantum mechanics and the particle-like properties of a photon. The photoionization cross sections of H atom and H-like ions, He atom and He…
A hot central star illuminating the surrounding ionized H II region usually produces very rich atomic spectra resulting from basic atomic processes: photoionization, electron-ion recombination, bound-bound radiative transitions, and…
We compare numerical methods for solving the radiative transfer equation in the context of the photoionization of intergalactic gaseous hydrogen and helium by a central radiating source. Direct integration of the radiative transfer equation…
We present a detailed model of the discrete X-ray spectroscopic features expected from steady-state, low-density photoionized plasmas. We apply the Flexible Atomic Code (FAC) to calculate all of the necessary atomic data for the full range…
Multiphoton ionization provides a clear window into the nature of electron correlations in the helium atom. In the present study, the final state energy range extends up to the region near the $N=2$ and $N=3$ ionization thresholds, where…