Quantum Defect Orbital Method Research Articles

Intensities for Transitions Involving Highly Excited States of Nii: A Relativistic Treatment

Astrophysically relevant transitions involving excited states in singly ionized nitrogen have been studied, some of them for the first time in the LK-coupling scheme. The Relativistic Quantum Defect Orbital method has been employed. Oscillator strengths and transition probabilities for the fine-structure lines of a number of transition arrays are reported and analyzed.

Fine‐Structure Transitions of Si ii with Interest in Astrophysics

Oscillator strengths of the dipole-allowed fine-structure transitions in Si II between the terms belonging to the 3s2 nl (n = 3-10) and l = 0-3 configurations have been calculated in the LS-coupling scheme using the Relativistic Quantum Defect Orbital method, with and without accounting explicitly for the core-valence correlation. The present f-values are compared with other available results for this astrophysically important ion, and good agreement has been found.

Atomic Data for Allowed Spectral Lines of Cl+3and Ar+4

Oscillator strengths and Einstein coefficients of allowed spectral lines of the silicon-like ions, Cl+3 and Ar+4 that are relevant in astrophysics have been calculated in the LSJ-coupling scheme using the relativistic quantum defect orbital (RQDO) method. For some transitions of Cl+3, these data are being reported for the first time.

Oscillator strengths for spectral lines of Zr III of astrophysical importance

The spectrum of Zr III has been observed in the chemically peculiar B-type star Chi Lupi with the Goddard high-resolution spectrograph on the Hubble space telescope. Oscillator strengths for the dipole-allowed fine-structure transitions in Zr III between the levels belonging to the 4d2 and 4dnl (n = 4-6 and l = 1-3) configurations, which may be useful for abundance determinations, have been calculated in the LSJ-coupling scheme using the relativistic quantum-defect orbital method, with and without explicit account for core-valence correlation. For some of the studied fine-structure transitions the presently calculated f-values are the only ones available in the literature.

The spectrum of NeH: A comparative isoelectronic study

Einstein coefficients and oscillator strengths for Rydberg–ground and Rydberg–Rydberg transitions in the rare-gas excimer NeH have been calculated with the quantum defect orbital (QDO) method. A comparative study of analogous transitions in NeH and in some of its isoelectronic Rydberg radicals has revealed clear similarities between them.

Analysis of the Triplet Transitions from the \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $3d^{2}$ \end{document} Configuration in Fevii

Oscillator strengths for allowed 3d2-3d4p and 3d2-3dnf(n=4-10) absorption lines of Fe VII have been calculated using the relativistic quantum defect orbital (RQDO) method in the LS coupling scheme. These lines have important applications in the study of hot plasmas and astrophysical objects, and they have applications in tokamak devices. The agreement between the present data and those from the most recent and sophisticated available calculations is very good for many of the lines reported.

Quantum defect and transition probabilities

A summary of the relativistic quantum defect orbital (RQDO) method, as well as a few numerical examples of oscillator strengths, are presented. The radial functions in this formalism derive from solving a form of the decoupled second-order Dirac radial equation. With the method being totally analytical, it constitutes a simple and reliable procedure for predicting properties of interest in astrophysics and fusion plasma research, such as transition probabilities, while accounting for a large part of relativistic effects. Core polarization during electron transitions can also be explicitly accounted for in an analytic form.

Lifetime calculations in Yb II

Oscillator strengths and lifetime values for Yb II levels have been calculated within the framework of a pseudo-relativistic Hartree-Fock (HFR) approximation combined with a least-squares fitting of the calculated eigenvalues to the observed energy levels. A considerable amount of configuration interaction together with core-polarization effects have been included in the calculations. The quality of the HFR results has been assessed through a comparison with data obtained using the completely independent relativistic quantum defect orbital (RQDO) method. The theoretical lifetimes reported in the present paper are now in good agreement with most of the accurate experimental values available. The origin of the persisting discrepancies is suggested.

Oscillator strengths in the silicon sequence: Relativistic Quantum Defect Orbital and Multiconfigurational Dirac-Fock calculations

Oscillator strengths for and transitions in the silicon sequence (KVI - XeXLI) have been calculated using the Relativistic Quantum Defect Orbital (RQDO) method, with and without explicit inclusion of core-valence correlation, and the multiconfigurational Dirac-Fock (MCDF) approach. Our f -values, which are of interest in astrophysics and fusion plasma research, are compared with other theoretical results in the cases for which these are available.

Systematic in the relativistic oscillator strengths for fine-structure transitions in the aluminium isoelectronic sequence

Theoretical oscillator strengths for 3s 23p 2P-3s 23d 2D, 3s 23p 2P-3s 24s 2S and 3s 24s 2S-3s 24p 2P fine-structure transitions in some ions of the aluminium isoelectronic sequence are reported. The computations have been carried out with two formalisms within the context of quantum defect theory: the quantum defect orbital method (QDO) and its relativistic counterpart (RQDO). The advantages of including relativistic effects are made apparent. Some of these are reflected by the correct systematic trends displayed by the RQDO −values along the isoelectronic sequence.

Rydberg electron transitions in the methyl radical

Transition probabilities corresponding to one-photon transitions to Rydberg states of the methyl radical have been calculated with a molecular-adapted version of the quantum defect orbital (QDO) method. The results appear to be in accord with those of an analysis of the experimental spectrum by Herzberg.

Multi-configuration Dirac-Fock and relativistic quantum defect orbital study of triplet-triplet transitions in beryllium-like ions

Oscillator strengths for 2 s2 p 3 P-2 s3 d 3 D and 2 s2 p 3 P-2 s3 s 3 S fine structure transitions in beryllium-like ions ( Z = 4–36) have been calculated using both the Relativistic Quantum Defect Orbital (RQDO) method, with and without explicit inclusion of core-valence correlation, and the multiconfiguration Dirac-Fock (MCDF) approach. Our f-values, which are of interest in astrophysics and fusion plasma research, are compared with other theoretical and experimental results for the cases for which these are available.

Quantum defect orbital calculation of oscillator strengths for electronic transitions in triatomic hydrogen

Oscillator strengths for the H 3 Rydberg molecule have been calculated using a modified quantum defect orbital (QDO) method. The accuracy of this approach has been estimated by comparing its results with the data derived from more sophisticated ab initio methods and from an earlier, simplified, molecular version of the QDO method.

Quantum defect orbital study of electronic transitions in Rydberg molecules: ammonium and fluoronium radicals

Abstract Oscillator strengths and Einstein emission coefficients for NH 4 and H 2 F Rydberg radicals have been calculated using the quantum defect orbital method. An estimate of the accuracy of this approach has been obtained by a comparison of the results with the data derived from more sophisticated ab initio methods. In several cases, in particular for H 2 F molecule, predictions of unknown transition probabilities have been given. The method proved to be a reliable and useful tool to estimate transition probabilities between molecular Rydberg states.

Relativistic oscillator strengths for transitions in the principal spectral series of the silver isoelectronic sequence

In a very recent paper [1] we have reported oscillator strengths for fine structure transitions between levels belonging to the diffuse and sharp spectral series in the silver isoelectronic sequence. The calculations were performed with the quantum defect orbital method in both their non-relativistic (QDO) and relativistic (RQDO) formulations, with both implicit and explicit allowance for core-valence polarisation. We now present a parallel study of transitions belonging to thens2S−n′2P(n=5, 6;n′=5−10) spectral series of the AgI sequence, up toZ=63 in some cases.

Relativistic oscillator strengths for excited state transitions in some ions of the silver isoelectronic sequence

The relativistic quantum defect orbital method has been applied to the study of fine structure 5p2P-nd2D and 5p2P-ns2S (n≥5) transitions (some of them involving highly excited upper levels) in the silver isoelectronic sequence. The resulting oscillator strengths are analyzed in terms of other relativistic results and some available experimental data.

Electronic transitions in the Rydberg radical H3O

Oscillator strengths and Einstein emission coefficients for electronic transitions in the Rydberg molecule H3O are reported. The calculations have been performed with the Quantum Defect Orbital (QDO) method, and the results are compared with those of an ab initio procedure. © 1995 John Wiley & Sons, Inc.

Triplet-triplet transitions in zinc-like ions

Theoretical oscillator strengths are reported for the lines of the 4s4p3P-4s4d3D transition in some ions of the zinc isoelectronic sequence, which are of interest in fusion plasma research. The calculations have been performed with the relativistic quantum defect orbital (RQDO) method. A core-polarization to the dipole transitions moment has also been included in the formalism. A comparative study with other theoretical results and the scarce experimental measurements has also been carried out. Systematic trends of individual oscillator strengths along the isoelectronic sequence are also shown in a graphical form.

Isoelectronic smoothing of energy levels and calculations on the 2sns 1 S?2smp 1 P 0 transitions in the beryllium isoelectronic sequence

Oscillator strengths for 2sns1S→2smp1P0 transitions of several ions in the beryllium isoelectronic sequence (BeI- CrXXI) have been computed and analyzed. The quantum defect orbital method, including core-polarization effects through an effective dipole-moment transition operator, has been followed. Comparisons are made between various theoretical and experimental data and those predicted here. It is shown that the quantum defect orbital formalism adequately describes transitions in these atomic systems.

Relativistic quantum defect calculations on the copper isoelectronic sequence

AbstractThe quantum defect orbital (QDO) method and its relativistic (RQDO) counterpart have been employed in this work to compute oscillator strengths for several fine‐structure transitions in members of the copper isoelectronic sequence up to Z = 92. The RQDO results are found to be in quite good agreement with the best estimates derived from other sources, whenever the comparison is possible. © 1994 John Wiley & Sons, Inc.