Extreme Ultraviolet Transitions Research Articles

Spectroscopic study of EUV and SXR spectral lines with partition function and level population of W LVI

We present a comprehensive and elaborate study of W LVI (K-like W55+) by using multi-configuration Dirac–Fock method (MCDF). We have included relativistic corrections, QED (quantum electrodynamics) and Breit corrections in our computation. We have reported energy levels and radiative data for multipole transitions (i.e., electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2)) within the lowest 142 fine-structure levels and predicted soft X-ray transition (SXR) and extreme ultraviolet transitions (EUV) from higher excited states to the ground state. We have compared our calculated data with energy levels compiled by NIST and other available results in the literature and the small discrepancies found with them are discussed. Because only a few of the lowest levels are available in the literature, for checking excitation energies of higher excited states we have performed the same calculations with the distorted wave method. Furthermore, we have also provided relative population for the first five excited states, with both the partition function and thermodynamic quantities for W LVI and studied their variations with temperature. We believe that our reported new atomic data of W LVI may be useful in identification and analysis of spectral lines from various astrophysical and fusion plasma sources and may also be beneficial in plasma modeling.

Extended calculations for energies and EUV transition data of W LIII

Energy spectra of the 3d4, 3d34s, 3d34p, and 3d34d configurations of W LIII are calculated using the ab initio multi-configuration Dirac-Fock method. The correlations within the n = 9 complex, n being the principal quantum number of the outermost electron are accounted for in a systematic way and the Breit interaction and quantum electrodynamics effect are evaluated. Wavelengths, oscillator strengths, electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole emission transition rates regarding these levels are obtained. The Flexible Atomic Code (FAC) calculations are further performed to support these data. Results are compared with other available theory reported in the literature as well as the recommended experimental data listed in the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST) online database. Satisfactory agreement is found between them. In light of these findings, the present complete and consistent results can aid line identifications in extreme ultraviolet (EUV) spectra and should be beneficial in fusion plasma research.

Study of Relativistic excitation energies and transition data of X–ray and EUV transitions in Be-like ions

In the present work, fine structure energies, transition wavelengths, transition rates, oscillator strengths and line strengths have been presented for lowest 40 levels of Be-like Fe, Os to Hg ions by using GRASP2K. We have analyzed the effects of core-valence (CV) correlations in excitation energies as a function of active set. We accomplish that effects of core-valence correlations are necessary to attain accuracy and convergence in excitation energies. We have compared our presented excitation energies of Be-like Fe with available theoretical and experimental energies and found good agreement. But due to unavailability of data for Be-like Os to Hg ions for comparison, we have calculated excitation energies from flexible atomic code (FAC). We show that magnetic multipole transitions (M2) have effective contribution in lifetime of 2s3p 3P2o and 2p3d 3P2o. We demonstrate that transitions of Be-like ions among lowest 40 levels mainly occurs in Hard X-ray (HXR), Soft X-ray(SXR) and Extreme Ultraviolet (EUV) regions.

Extended atomic structure calculations for energy levels and radiative data of Xe XLIII

We report an extensive and elaborate theoretical study of atomic data for Xe XLIII. We have calculated energies for the lowest 141 fin. structure levels by using Multi-Configuration Dirac Fock (MCDF) method. We have also considered Quantum Electrodynamics (QED) and Breit corrections in our calculations. We have presented the radiative data for electric dipole (E1) transitions among lowest 141 levels. We have made comparisons of our calculated excitation energies and EUV (Extreme Ultraviolet) transition wavelengths with the theoretically computed and experimentally observed energy levels and wavelengths at Electron Beam Ion Trap (EBIT) and a good agreement is achieved. We have also computed energy levels by performing similar relativistic distorted wave calculations using Flexible Atomic Code (FAC). Additionally, we have provided new atomic data for Xe XLIII which are not published elsewhere in the literature. We believe that our results may be beneficial in fusion plasma research and detection and investigation of EUV and Soft X-ray (SXR) spectral lines.

Spectroscopic Study of EUV and SXR Transitions of Ba XLVI

An extensive set of energy levels, inverse radiative rates, wave-function composition in LSJ and JJ coupling schemes for the lowest 162 fine structure levels along with transition wavelengths, oscillator strengths, line strengths and transition probabilities for electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) EUV and SXR transitions from the ground state have been presented for Ba XLVI. For these calculations, the fully relativistic Multiconfiguration Dirac-Fock (MCDF) approach is employed. The QED corrections due to vacuum polarization and self-energy effects and Breit correction due to the exchange of virtual photons between two electrons are fully considered. To assess the authenticity and credibility of presented results, analogous calculations have also been performed by using a fully relativistic configuration interaction program (Flexible Atomic Code) based on self-consistent Dirac-Fock-Slater iteration method. Extreme Ultraviolet (EUV) and Soft X-ray (SXR) transitions are also identified. Comparison is also made with the available experimental and theoretical data. These accurate data are expected to be useful in fusion research and astrophysical investigations and applications.

Configuration interaction calculations and excitation rates of X-ray and EUV transitions in sulfurlike manganese

Fine-structure calculations of energies and transition parameters have been performed using the configuration interaction technique (CI) as implemented in CIV3 code for sulfurlike manganese, Mn X. The calculations are executed in an intermediate coupling scheme using the Breit-Pauli Hamiltonian. As well as, energy levels and oscillator strengths are calculated using LANL code, where the calculations by LANL have been used to estimate the accuracy of the present CI calculations. The calculated energy levels, oscillator strengths, and lifetimes are in reasonable agreement with the published experimental and theoretical values. Electron impact excitation rates of the transitions emit soft X-ray and extreme ultraviolet (EUV) wavelengths have been evaluated. The level population densities are calculated using the collisional radiative model (CRM), as well. The collisional excitation rates and collision strengths have been calculated in the electron temperature range ≤ the ionization potential, ∼1–250eV.

Energy levels, lifetimes and radiative data of Ba XXVI

We report an extensive and an elaborate theoretical study of atomic data for Ba XXVI by considering Singlet, Doublet and Triplet (SDT) electron excitations within N-shell and single excitations from N-shell to O-shell. We have calculated energy levels and lifetimes for lowest 110 fine structure levels by using Multi-configuration Dirac–Fock method (MCDF). We have also considered Quantum Electrodynamics (QED) and Breit corrections in our calculations. We have presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions among lowest 110 levels. We have made comparisons of our calculated excitation energies and EUV (Extreme Ultraviolet) transition wavelengths with experimentally observed energy levels and wavelengths and achieved good agreement. We have also computed energy levels by performing similar relativistic distorted wave calculations using Flexible Atomic Code (FAC). Additionally, we have provided new atomic data for Ba XXVI which are not published elsewhere in the literature. We believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

Ultraviolet and extreme-ultraviolet line ratio diagnostics for O IV

Aims. We generate theoretical ultraviolet and extreme-ultraviolet emission line ratios for O iv and show their strong versatility as electron temperature and density diagnostics for astrophysical plasmas. Methods. Recent fully relativistic calculations of radiative rates and electron impact excitation cross sections for O iv, supplemented with earlier data for A-values and proton excitation rates, are used to derive theoretical O iv line intensity ratios for a wide range of electron temperatures and densities. Results. Diagnostic line ratios involving ultraviolet or extreme-ultraviolet transitions in O iv are presented, that are applicable to a wide variety of astrophysical plasmas ranging from low density gaseous nebulae to the densest solar and stellar flares. Comparisons with observational data, where available, show good agreement between theory and experiment, providing support for the accuracy of the diagnostics. However, diagnostics are also presented involving lines that are blended in existing astronomical spectra, in the hope this might encourage further observational studies at higher spectral resolution.

Estimation of soft X-ray and EUV transition radiation power emitted from the MIRRORCLE-type tabletop synchrotron

The tabletop synchrotron light sources MIRRORCLE-6X and MIRRORCLE-20SX, operating at electron energies E(el) = 6 MeV and E(el) = 20 MeV, respectively, can emit powerful transition radiation (TR) in the extreme ultraviolet (EUV) and the soft X-ray regions. To clarify the applicability of these soft X-ray and EUV sources, the total TR power has been determined. A TR experiment was performed using a 385 nm-thick Al foil target in MIRRORCLE-6X. The angular distribution of the emitted power was measured using a detector assembly based on an NE102 scintillator, an optical bundle and a photomultiplier. The maximal measured total TR power for MIRRORCLE-6X is P(max) approximately equal 2.95 mW at full power operation. Introduction of an analytical expression for the lifetime of the electron beam allows calculation of the emitted TR power by a tabletop synchrotron light source. Using the above measurement result, and the theoretically determined ratio between the TR power for MIRRORCLE-6X and MIRRORCLE-20SX, the total TR power for MIRRORCLE-20SX can be obtained. The one-foil TR target thickness is optimized for the 20 MeV electron energy. P(max) approximately equal 810 mW for MIRRORCLE-20SX is obtained with a single foil of 240 nm-thick Be target. The emitted bremsstrahlung is negligible with respect to the emitted TR for optimized TR targets. From a theoretically known TR spectrum it is concluded that MIRRORCLE-20SX can emit 150 mW of photons with E > 500 eV, which makes it applicable as a source for performing X-ray lithography. The average wavelength, \overline\lambda = 13.6 nm, of the TR emission of MIRRORCLE-20SX, with a 200 nm Al target, could provide of the order of 1 W EUV.

Extreme ultraviolet transitions of Fe xxi in solar, stellar and laboratory spectra

Recent R-matrix calculations of electron impact excitation rates for transitions among the 2s22p2, 2s2p3 and 2p4 levels of Fe xxi are used to derive theoretical electron density (Ne) sensitive emission-line ratios involving 2s22p2–2s2p3 transitions in the ∼98–146A wavelength range. A comparison of these with observations from the PLT tokamak plasma, for which the electron density has been independently determined, reveals generally very good agreement between theory and experiment, and in some instances removes discrepancies found previously. The observed Fe xxi ratios for a solar flare, obtained with the OSO–5 satellite, imply electron densities which are consistent, with discrepancies that do not exceed 0.2 dex. In addition, the derived values of Ne are similar to those estimated for the high-temperature regions of other solar flares. The good agreement between theory and observation, in particular for the tokamak spectra, provides experimental support for the accuracy of the present line-ratio calculations, and hence for the atomic data on which they are based.