Photoionization of Al-like Si using the R-matrix method

2011 ◽  
Vol 89 (11) ◽  
pp. 1119-1126 ◽  
Author(s):  
Jagjit Singh ◽  
Sunny Aggarwal ◽  
A.K.S. Jha ◽  
A.K. Singh ◽  
M. Mohan
Keyword(s):  
Cross Sections ◽  
Matrix Method ◽  
Relativistic Effects ◽  
Coupling Scheme ◽  
Rydberg Series ◽  
Channel Coupling ◽  
R Matrix ◽  
Practical Applications ◽  
Physical Effects ◽  
Ionic States

Relativistic calculations are made for photoionization of the ground state 3s23p ([Formula: see text]) and the lowest six excited states 3s23p ([Formula: see text]), 3s3p2 (4P1/2,3/2,5/2), and 3s3p2 (2D3/2,5/2) of Al-like Si, using the Breit–Pauli Hamiltonian within the R-matrix method. Cross sections are determined by the Rydberg series of autoionizing resonances converging to various ionic states. Relativistic effects as well as all the important physical effects like exchange, channel coupling, and short-range correlations have been considered in the present calculations. The present relativistic calculations for this ion using the lowest 20 target levels of Si III in the LSJ coupling scheme will enhance the database sufficiently for practical applications of photoionization cross sections of Si II.

Photoionization of ground 1s2 2s2 2p6 1Se0 and excited 1s2 2S22p53S 3Po0,1,2 states of Si V using relativistic Breit–Pauli R-matrix method

2006 ◽  
Vol 84 (8) ◽  
pp. 707-715 ◽  
Author(s):  
AK S Jha ◽  
N Singh ◽  
N Verma ◽  
M Mohan
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Configuration Interaction ◽  
Matrix Method ◽  
Relativistic Effects ◽  
Wave Functions ◽  
Close Coupling ◽  
R Matrix ◽  
Matrix Expansion ◽  
Target States

The close-coupling R-matrix method has been used to calculate photoionization cross sections for the ground and the lowest three excited states using the relativistic Breit–Pauli approximation. Configuration interaction wave-functions are used to represent eleven lowest LSJ target states of Si VI retained in the R-matrix expansion. Relativistic effects are clearly revealed from resonance converging on the excited states of Si VI.PACS No.: 32.80.Fb

scholarly journals Relativistic B-Spline R-Matrix Calculations for Electron Collisions with Ytterbium

Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 47
Author(s):  
Kathryn R. Hamilton ◽  
Klaus Bartschat ◽  
Oleg Zatsarinny
Keyword(s):  
Experimental Data ◽  
Electron Scattering ◽  
Cross Sections ◽  
Matrix Method ◽  
Model Potential ◽  
Electron Collisions ◽  
R Matrix ◽  
B Spline ◽  
Potential Approach

We have applied the full-relativistic Dirac B-Spline R-matrix method to obtain cross sections for electron scattering from ytterbium atoms. The results are compared with those obtained from a semi-relativistic (Breit-Pauli) model-potential approach and the few available experimental data.

scholarly journals Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 27
Author(s):  
Jean-Paul Mosnier ◽  
Eugene T. Kennedy ◽  
Jean-Marc Bizau ◽  
Denis Cubaynes ◽  
Ségolène Guilbaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Rydberg Series ◽  
R Matrix ◽  
Resonance Strengths ◽  
Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

Photoionization of Al X from ground state using the relativistic R-matrix close-coupling method

2014 ◽  
Vol 92 (3) ◽  
pp. 241-245 ◽  
Author(s):  
Liang Liang ◽  
Xu-yang Liu ◽  
Chao Zhou
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Energy Levels ◽  
Resonance Energy ◽  
Photoionization Cross Section ◽  
Rydberg Series ◽  
Close Coupling ◽  
R Matrix ◽  
Target States ◽  
Distorted Wave Method

The relativistic R-matrix method is used to calculate the total photoionization cross sections from the ground state 1s22s2 1S0 of Al X for photon energies ranges from the first ionization threshold to just above the eighth threshold of the residual ion Al XI. In this work, the relativistic distorted-wave method is employed to calculate the fine-structure energy levels and radial functions. The lowest eight level target states of Al XI are used in the photoionization calculations of Al X and should provide a reasonably complete database for practical application for photoionization cross section for Al X. The resonance energy levels and widths of 18 Rydberg series have been investigated.

Theoretical photoionization study of Ti9+ ion

2020 ◽  
Author(s):  
Hongbin Wang ◽  
Gang Jiang
Keyword(s):  
Cross Sections ◽  
Energy Levels ◽  
Radiative Transition ◽  
High Energy ◽  
Low Energy ◽  
Transition Rates ◽  
Channel Coupling ◽  
R Matrix ◽  
Good Consistency ◽  
Good Agreement

Photoionization (PI) of Ti<sup>9+</sup> ion is investigated by the Dirac R-matrix method. Multi-Configuration Dirac-Fock (MCDF) calculations are performed to construct accurate target functions. Good agreement of energy levels and radiative transition rates indicate the accuracy of target functions. PI cross sections show good consistency between length and velocity forms. The results are consistent with the previous theoretical values in high-energy regions. Partial waves contribution to the total PI cross sections are discussed for the ground and metastable states. Moreover, the PI cross sections are dominated by many resonance structures and affected by the channel coupling effects in low-energy region. In addition to providing data for the Opacity Project TOPbase, the present work promotes plasma simulation and diagnosis.

scholarly journals Partial Photoionization Cross Sections of Chromium from the Ground and Excited States

Atoms ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 51
Author(s):  
Oleg Zatsarinny ◽  
Swaraj Tayal
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Bound States ◽  
Close Coupling ◽  
R Matrix ◽  
Hartree Fock ◽  
Nonresonant Background ◽  
Ionic States ◽  
Matrix Calculation

Partial and total photoionization cross sections of iron-peak elements are important for the determination of abundances in late-type stars and nebular objects. We have investigated photoionization of neutral chromium from the ground and excited states in the low energy region from the first ionization threshold at 6.77 eV to 30 eV. Accurate descriptions of the initial bound states of Cr I and the final residual Cr II ionic states have been obtained in the multiconfiguration Hartree-Fock method together with adjustable configuration expansions and term-dependent non-orthogonal orbitals. The B-spline R-matrix method has been used for the calculation of photoionization cross sections. The 194 LS final ionic states of Cr II 3d44s, 3d34s2, 3d5, 3d44p, and 3d34s4p principal configurations have been included in the close-coupling expansion. The inclusion of all terms of these configurations has significant impact on the near-threshold resonance structures as well as on the nonresonant background cross sections. Total photoionization cross sections from the ground 3d54sa7S and excited 3d54sa5S, 3d44s2a5D, 3d54pz5P, and 3d44s4py5P states of Cr I have been compared with other available R-matrix calculation to estimate the likely uncertainties in photoionization cross sections. We analyzed the partial photoionization cross sections for leaving the residual ion in various states to identify the important scattering channels, and noted that 3d electron ionization channel becomes dominant at higher energies.

NON-FRANCK–CONDON EFFECTS IN THE PHOTOIONIZATION OF N2 TO THE ${\rm N}_2^+$ A 2Πu STATE AND OF O2 TO THE ${\rm O}_2^+$ X 2Πg STATE IN THE 19–34 eV PHOTON ENERGY REGION

2002 ◽  
Vol 09 (01) ◽  
pp. 147-152
Author(s):  
J. RIUS I RIU ◽  
J. ÁLVAREZ ◽  
A. KARAWAJCZYK ◽  
M. STANKIEWICZ ◽  
P. WINIARCZYK ◽  
...  
Keyword(s):  
Cross Sections ◽  
Photoelectron Spectroscopy ◽  
Branching Ratios ◽  
Rydberg Series ◽  
Many Body ◽  
Channel Coupling ◽  
Valence States ◽  
Many Body Perturbation Theory ◽  
First Time ◽  
Franck Condon

Photoionization to the [Formula: see text] A 2Πu state and to the [Formula: see text] X 2Πg state is studied using photoelectron spectroscopy. The experimental vibrational branching ratios are obtained for the first time in the 19–34 eV region for the v′ = 0–3 levels, for both molecules. Ab initio many-body perturbation theory is used to calculate branching ratios for ionization to the [Formula: see text] A 2Πu state and branching ratios, vibrationally resolved partial cross sections and total cross section for ionization to the [Formula: see text] X 2Πg state. The Franck–Condon breakdown observed in the photoionization of the N 2 1πu electron is mainly explained by autoionization from Rydberg and valence states of N 2, whereas photoionization of the O 2πg electron is not fully explained either by channel coupling effects or by autoionization from known Rydberg series and valence states.

Autoionisation in Atomspektren

1968 ◽  
Vol 23 (1) ◽  
pp. 137-151
Author(s):  
F. J. Comes ◽  
H. G. Sälzer ◽  
G. Schumpe
Keyword(s):  
Numerical Calculation ◽  
Cross Sections ◽  
Line Shape ◽  
Shape Parameter ◽  
Atomic Gases ◽  
Rare Gases ◽  
Rydberg Series ◽  
Ionic States ◽  
Line Shape Parameter ◽  
Absorption Measurements

A detailed discussion of the phenomenon of autoionization and its influence on the absorption spectra of atomic gases is given. Some consideration is devoted to the calculation of cross sections. This theory is applied to the autoionizing Rydberg levels lying above the 2P3/2 threshold of the rare gases krypton and xenon. A numerical calculation is decribed which alows the important parameters of Rydberg series to be calculated. These parameters are the so called unperturbed continuum, the lifetime and oscillator strength of the autoionizing states, the line shape parameter and the quantum defect. From absorption measurements in argon and krypton considerations follow concerning the behaviour of these terms at threshold. A further result of the calculations is the transition probality into the ionic states 2P3/2 and 2P1/2 at the 2P1/2 limit. These values are compared with measured intensities of photoelectrons from a retarding potential experiment.

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