Radiative Transition Parameters Research Articles

On detection of BaO molecular lines in sunspot spectrum

ContextSpectral lines of diatomic molecules are perfect tools for studying the structure of sunspots and their temperature layers and magnetic sensitive absorption features, which are typically higher than in atomic lines. The integrated intensities of a few bands in the rotational structure of the astrophysically significant A1Σ+−X1Σ+and A′1Π−X1Σ+ systems of barium monoxide (BaO) have been measured experimentally using band spectra. An analysis of the prominent lines of (0, 0; 1, 1; 2, 2) bands of A1Σ+−X1Σ+transition and (0, 0; 1, 1; 2, 2) bands of A′1Π−X1Σ+transition with those of sunspot umbral spectrum. The effective rotational temperatures of the A′1Π−X1Σ+transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K. AimsAn analysis of BaO prominent rotational molecular lines of A1Σ+−X1Σ+and A′1Π−X1Σ+transition with those of sunspot umbral spectral lines. To find the significant values of radiative transition parameters, vibrational temperature and the effective rotational temperature of the molecule in celestial objects. MethodsCalibrated the rotational structure of molecular band heads and lines for and A1Σ+−X1Σ+and A′1Π−X1Σ+ransitions in laboratory spectrum using most precise Hartmann's technique. High resolution FTS sunspot umbral spectra from NSO/Kitt Peak were used to detect rotational molecular lines due to the A′1Π−X1Σ+transition of the BaO molecule using the method of line coincidence. The effective rotational temperature was derived from the variation of equivalent width (W) with rotational quantum number (J) of spectrally well resolved rotational lines of a band in umbral spectrum. The triangular profile approximation method was used to estimate the equivalent width of the well resolved spectral lines. ResultsThe effective rotational temperatures of the A′1Π−X1Σ+transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K. It is compared with other results with a view to obtaining useful physical parameters. This is an evidence to ascertain the possible presence of BaO molecule in solar spectrum in different layers. ConclusionsUnblended rotational lines due to the band of BaO, provide a good range of temperatures for the study of absorbing layers in umbral spectra. The A′1Π−X1Σ+transition of BaO molecular lines is found to be very sensitive to effective temperature. Radiative transition parameters data of these lines, in contrast to intensity measurements, provide us with more direct and detailed information to study the coolest parts of sunspot umbrae.

Atomic Data for Astrophysically Important Spectral Lines of Singly Ionized Nitrogen

Nitrogen lines are widely observed in astrophysical spectra and provide important diagnostics for plasma properties. In this work, we present extended calculations for accurate energy levels, electric dipole radiative transition parameters, and lifetimes for the lowest 102 states of the 2s 22p 2, 2s2p 3, 2s2p 23s, 2s 22p{n 1 l, n 2 d, 4f}(n 1 = 3–5, l = s, p, n 2 = 3, 4), and 2p 4 configurations of N ii within the framework of the fully relativistic multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods. These data are useful for modeling astrophysical spectra, for example, for nitrogen abundance determinations in early B-type stars, and for studying the compositions and plasma properties of H ii regions and planetary nebulae. Our computed transition parameters are compared with available experimental and theoretical data. The accuracy of the calculations is also assessed via a statistical analysis of the differences between the transition rates in the Babushkin and Coulomb gauges and by consideration of cancellation factors. In this way, 201 of the 1656 transitions computed in this work are estimated to be from accurate to better than 3%, corresponding to an accuracy class of A.

On the effective vibrational temperature of the source using (2)3∏ - X3∏ system of GeC molecule

In this work, the experimental potential energy curves for (2)3Π and X3Π electronic states of GeC molecule have been constructed by using Rydberg-Klein-Rees (RKR) method. The radiative transition parameters viz., Franck-Condon (FC) factor, r-centroid, electronic transition moment, band strength, relative band strength, Einstein coefficients, radiative lifetime and oscillator strength for the (2)3Π−X3Π system of GeC molecule have been estimated for the experimentally observed vibrational levels from Rydberg-Klein-Rees (RKR) potential and the estimated values are tabulated. The estimated effective vibrational temperature found as 5628 K for the (2)3Π−X3Π system of GeC molecule. The radiative transition parameters and effective vibrational temperature are evident that the possible presence of GeC molecule in solar and sunspots atmosphere. Further, these parameters are employed in rationalizations of astrochemical and astrophysical observations.

Study of optical, structural and radiation shielding properties of (55 − x)TeO2–20ZnO–25B2O3–xEr2O3 glass matrix

Abstract Erbium doped zinc boro-tellurite (EZBT) glass samples with molar composition of (55 − x)TeO2–20ZnO–25B2O3–xEr2O3 (x = 0.0, 0.5, 1.0, 1.5 and 2.0 mol.%) were prepared by a conventional melt quenching technique. The prepared samples were characterised using X-ray diffraction, Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy techniques to investigate the structural, optical and dielectric properties. To study the radiation shielding capabilities, the parameters such as mass attenuation coefficient (μ m), half-value layer (HVL), effective atomic number (Z eff) etc., were evaluated using WinXCom software. Judd–Ofelt analysis was carried out to determine the intensity of electronic transitions and other radiative transition parameters within the 4f shell of erbium ions. The μ m values in a range of (108.5–0.03) cm2 g−1 for energy range (0.01–10) MeV were obtained for 2.0 mol.% erbium-doped tellurite glass matrix. The μ m and HVL values were also compared with conventionally used ordinary concrete and specific lead borate glass at certain energies. The detailed investigation of this current EZBT glass matrix is very useful in the specific optical and radiation shielding applications of this EZBT glass.

Energy Levels and Transition Data of Cs VI

Previously reported atomic data (spectral lines, wavelengths, energy levels, and transition probabilities) were collected and systematically analyzed for Cs VI. The present theoretical analysis was supported by extensive calculations made for Cs VI with a pseudo-relativistic Hartree–Fock (HFR) method together with the superposition of configuration interactions implemented in Cowan’s codes. In this work, all previously reported energy levels and their (allowed) transition assignments were confirmed. A critically evaluated set of optimized energy levels with their uncertainties, observed and Ritz wavelengths along with their uncertainties, and theoretical transition probabilities with their estimated uncertainties were presented in the compilation. In addition to this, we determined the radiative transition parameters for several forbidden lines within the ground configuration 5s25p2 of Cs VI.

Lisbon Atomic Database (LISA): a compilation of calculated fundamental atomic parameters

The Lisbon Atomic Database (LISA) has a dedicated mission of compiling and providing a comprehensive collection of atomic parameters for the study of the interaction of X-rays with matter. This encompassing array of parameters spans a broad spectrum, extending from the calculation of electron impact ionization cross sections (EIICS) using the Modified Relativistic Binary Encounter Bethe model (MRBEB) , to pivotal data such as fluorescence and Coster–Kronig yields of atomic subshells, binding energies, and the full suite of radiative and non-radiative atomic transition parameters. Except for the EIICS values, all these parameters are obtained through ab initio calculations. These calculations are carried out using a self-consistent ab initio Multi-Configuration Dirac–Fock approach, supported by a specialized code developed by Desclaux, Indelicato, and others (MCDFGME).Graphical abstract

Critically Evaluated Atomic Data for the Au iv Spectrum

A spectral investigation of triply ionized gold (Au iv) has been carried out in the wavelength region of 500–2106 Å. The gold spectra were photographed at the National Institute of Standards and Technology, USA, on a 10.7 m normal incidence vacuum spectrograph (NIVS) using a sliding spark source as well as on a 3 m NIVS at the Antigonish laboratory in Canada with a triggered spark source. Our analysis is theoretically supported by the pseudorelativistic Hartree–Fock (HFR) formalism with a superposition of configuration interactions implemented in Cowan's suite of codes. Radiative transition parameters are also calculated using the HFR+CPOL (core polarization effects) model and the multiconfiguration Dirac–Hartree–Fock approach, and their comparisons are used to evaluate the transition rate data. All the previously reported levels of the 5d 8, 5d 76s, and 5d 76p configurations are confirmed, except one, and three are newly established. The missing 1 S 0 level of 5d 8 is now established at 55,277.8 cm−1. A total of 981 observed lines (E1 type), classified to 1031 transitions, including 133 newly identified, enabled us to optimize 139 energy levels. Several astrophysically important transitions, forbidden (M1- and E2-type) lines of 5d 8 and 5d 76s, are provided with their Ritz wavelengths and radiative parameters. A critically evaluated set of energy levels, observed and Ritz wavelengths along with their uncertainties, transition rates, and uniformly scaled intensities of Au iv lines have been presented. Also, large-scale atomic data to compute the opacity of Au iv in the kilonova ejecta have been supplemented in this work.

On the effective temperature of large sunspot umbra using AlH molecular lines

In this work, the radiative transition parameters including Franck–Condon (FC) factors, r-centroids, electronic transition moment, Einstein coefficients, band strength, oscillator strength, lifetime and effective vibrational temperature have been computed for A1Π−X1Σ+ and C1Σ+−A1Π systems of aluminium monohydride (AlH) molecule by the numerical integration method for the experimentally known vibrational levels using Rydberg – Klein – Rees (RKR) potential. The computed radiative transition parameters are tabulated. A significant number of well resolved AlH molecular rotational lines of A1Π−X1Σ+ (0,0), (1,1) and (0,1) bands are identified in the sunspot umbral spectrum and the estimated effective rotational temperature has been determined as 2315 K, 2155 K and 1838 K respectively. The effective vibrational temperatures of the A1Π−X1Σ+ and C1Σ+−A1Π systems are found to be 5682 K and 3472 K respectively. Hence, the radiative transition parameters and the effective temperatures confirm the presence of AlH molecule in sunspot spectra.

Large-scale Multiconfiguration Dirac–Hartree–Fock Calculations for Astrophysics: C-like Ions from O iii to Mg vii

Large-scale multiconfiguration Dirac–Hartree–Fock calculations are provided for the n ≤ 5 states in C-like ions from O iii to Mg vii. Electron correlation effects are accounted for by using large configuration state function expansions, built from sets of orbitals with principal quantum numbers n ≤ 10. An accurate and complete data set of excitation energies, wavelengths, radiative transition parameters, and lifetimes is offered for the 156 (196, 215, 272, 318) lowest states of the 2s 22p 2, 2s2p 3, 2p 4, 2s 22p3s, 2s 22p3p, 2s 22p3d, 2s2p 23s, 2s2p 23p, 2s2p 23d, 2p 33s, 2p 33p, 2p 33d, 2s 22p4s, 2s 22p4p, 2s 22p4d, 2s 22p4f, 2s2p 24s, 2s2p 24p, 2s2p 24d, 2s2p 24f, 2s 22p5s, 2s 22p5p, 2s 22p5d, 2s 22p5f, and 2s 22p5g configurations in O iii (F iv, Ne v, Na vi, Mg vii). By comparing available experimental wavelengths with the MCDHF results, the previous line identifications for the n = 5, 4, 3 → n = 2 transitions of Na vi in the X-ray and EUV wavelength range are revised. For several previous identifications discrepancies are found, and tentative new (or revised) identifications are proposed. A consistent atomic data set including both energy and transition data with spectroscopic accuracy is provided for the lowest hundreds of states for C-like ions from O iii to Mg vii.

Comprehensive Calculations of Energy Levels, Radiative Transition Parameters, Hyperfine Structure Constants Aj - Bj, Land´E Gj Factors and Isotope Shifts for Sc Xx

Comprehensive Calculations of Energy Levels, Radiative Transition Parameters, Hyperfine Structure Constants Aj - Bj, Land´E Gj Factors and Isotope Shifts for Sc Xx

Comprehensive Calculations of Energy Levels, Radiative Transition Parameters, Hyperfine Structure Constants Aj - Bj, Land´E Gj Factors and Isotope Shifts for Sc Xx

Comprehensive Calculations of Energy Levels, Radiative Transition Parameters, Hyperfine Structure Constants Aj - Bj, Land´E Gj Factors and Isotope Shifts for Sc Xx

On the effective temperature of AlC molecular lines in sunspot umbral spectra

In the present work, a significant rotational lines of the $B^{4}\Sigma ^{-} \mbox{--} X^{4}\Sigma ^{ -} $ ( $0,0$ ) band system of the AlC molecule were identified in high resolution FTS sunspot umbral spectra in the region from 22,450 to 22,600 cm−1. Among the well-resolved identified lines, the rotational temperatures have been estimated to be 4018 K for photosphere and 3722 K for a hot umbra. Hence, the estimated effective rotational temperatures provide evidence for the possible presence of the AlC molecule in a sunspot umbra. The radiative transition parameters for $A^{4}\Pi ^{ -} \mbox{--} X^{4}\Sigma ^{ -} $ and $B^{4}\Sigma ^{ -} \mbox{--} X^{4}\Sigma ^{ -} $ systems of the AlC molecule have been estimated for experimentally known vibrational levels using the Rydberg–Klein–Rees (RKR) potential. The Franck-Condon (FC) factor of $B^{4}\Sigma ^{ -} \mbox{--} X^{4}\Sigma ^{ -} $ ( $0,0$ ) band system is most intense ( $q_{v'v''} = 0.741$ ). For the $B^{4}\Sigma ^{ -}$ state, the radiative lifetime of $v'=0$ level is found as 103.93 ns. The effective vibrational temperature of the $A^{4}\Pi ^{ -} \mbox{--} X^{4}\Sigma ^{ -} $ and $B^{4}\Sigma ^{ -} \mbox{--} X^{4}\Sigma ^{ -} $ band systems of the AlC molecule is 3981 K and 2706 K, respectively. Therefore, the effective vibrational temperature and radiative transition parameters help us to ascertain the possible presence of the AlC molecule in the solar atmosphere.

Single-photon photoionization of highly charged ions under warm- and hot-dense plasmas using a unified description of screening

We present a detailed investigation of the spectral properties and photoionization of highly charged ions subjected to warm- and hot-dense plasma environments. A unified framework, based on the finite-temperature orbital-free density functional theory, is adopted to describe (warm- and hot-dense) plasma screening effects on the nucleus-electron interaction. Self-consistent solving the coupled radial Diarc equations for both bound and continuum wave functions is used through the model, EPPP, we developed, to account the relativistic and plasma shielding effects, which is based on the flexible atomic code. The key features of the proposed model are the capacities to systematically include gradient corrections and exchange-correlation effects. Additionally, numerical tests are conducted to validate the accuracy and stability of the model. The transition energies, radiative transition parameters, ionization potentials, and photoionization (radiation recombination) cross sections of an exemplary ion Al12+are studied under finite temperature and density conditions. The present work offers an insight into electron screening of ions and is expected to be beneficial for plasma modeling.

Broadband flat near-infrared emission from tellurite glass doped with Tm3+, Er3+ and Ag NPs

Tellurite glasses doped with trivalent Tm3+, Er3+ ions and metal Ag nanoparticles (NPs) were synthesized by single-step melt-quenching technique, and the near-infrared photoluminescence property was investigated. Differential scanning calorimeter (DSC) curve, X-ray diffraction (XRD) pattern, transmission electron microscopy (TEM) image, absorption spectrum, emission spectrum and fluorescence decay curve were measured. The good thermal stability and amorphous state nature of the as-prepared tellurite glasses were demonstrated by the DSC curve and XRD pattern, respectively. Absorption spectrum disclosed the electronic transitions in the ultraviolet to near-infrared spectral range and was further used to evaluate the potential in near-infrared band luminescence by the calculations of spontaneous radiative transition parameters and gain cross-sections of Tm3+(Er3+) ions. Under the excitation of 808 nm laser diode (LD), a broadband flat near-infrared emission with FWHM of approximately 160 nm was obtained in the Tm3+/Er3+ doped tellurite glass. This broadband flat near-infrared emission, originating from the spectral overlapping of Tm3+:3H4→3F4 transition (~1.47 µm) and Er3+:4I13/2 → 4I15/2 transition (~1.53 µm), was located in the 1350–1650 nm region and covered the E + S + C + L-bands simultaneously. With the precipitation of Ag NPs having diameter in the 10–20 nm range evidenced by TEM image in the Tm3+/Er3+ doped tellurite glass, the peak luminescent intensity increased by about 45%, which is attributed to the increased local electric field and the possible energy transfer from the Ag species to Tm3+(Er3+) ions. The obtained results demonstrate that Tm3+/Er3+/Ag NPs doped tellurite glass is prospective for broadband optical amplifiers, broadband lighting sources and so on.

Enhanced 1–5 μm near- and mid-infrared emission in Ho3+/Yb3+ codoped TeO2-ZnF2 oxyfluorotellurite glasses

Intense 1–5 μm infrared emission from near- to mid-infrared was obtained from Ho3+/Yb3+ codoped TeO2-ZnF2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation, and the emission intensity can be enhanced with the increase of ZnF2 content. Judd-Ofelt analysis was used to evaluate the radiative transition parameters of the excited levels according to the absorption spectra. The stimulated emission cross section of 5I6→5I8 (1.2 μm), 5I7→5I8 (2.0 μm), 5I6→5I7 (2.85 μm) and 5I5→5I6 (4.0 μm) transitions were calculated to reach 0.639 × 10–20, 0.760 × 10–20, 0.985 × 10–20 and 0.484 × 10−20 cm2, respectively. The energy transfer coefficients (CDA) are enhanced with the increase of ZnF2 content and phonon contribution ratios of phonon assisted energy transfer process between Ho3+ and Yb3+ were figured out. Our results demonstrate that these TeO2-ZnF2 glasses, which possess good thermal stability and transparency, low phonon energy (about 600 cm−1), excellent near- and mid-infrared emission in the range of 1–5 μm wavelength, would be promising material for infrared optical fibers and infrared lasers.

Radiative Transition Parameters in Atomic Lanthanum from Pseudo-Relativistic Hartree–Fock and Fully Relativistic Dirac–Hartree–Fock Calculations

Calculated radiative transition probabilities and oscillator strengths are reported for 392 lines of neutral lanthanum (La I) atom in the spectral range from the near ultraviolet to the mid infrared. They were obtained using two different theoretical methods based on the pseudo-relativistic Hartree–Fock (HFR) and the fully relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) approaches, both including the most important intravalence and core-valence electron correlations. The quality of these radiative parameters was assessed through detailed comparisons between the results obtained using different physical models and between our theoretical results and the experimental data, where available. Of the total number of La I lines listed in the present work, about 60% have gf- and gA-values determined for the first time.

Presence of C2 molecular Lines in Sunspot Umbral Spectra

The C2 molecule is well known for its astrophysical importance. The radiative transition parameters that include Franck-Condon (FC) factor, r-centroid, electronic transition moment, Einstein coefficient, absorption band oscillator strength, effective temperatures and radiative life time have been estimated for the Swan band (d3Πg−a3Πu) system of C2 molecule for experimentally observed vibrational levels using RKR (Rydberg–Klein–Rees) potential energy curve. The lifetime for the d3Πg state of C2 molecule was found to be 82.36ns for the v′=0 level. A reliable numerical integration method has been used to solve the radial Schrödinger equation for the vibrational wave functions of upper and lower electronic states based on the latest available spectroscopic data and known wavelengths. The estimated radiative transition parameters are tabulated. The effective vibrational temperature of Swan band system of C2 molecule is found agreed with the effective rotational temperature from photosphere spectrum. Hence, the radiative transition parameters and effective temperatures help us to ascertain the presence of C2 molecule in the interstellar medium, photosphere and sunspots.

Fourier Grid Hamiltonian Method for calculating the Einstein coefficients, Franck–Condon factors, r-Centroids, average internuclear separations and radiative lifetimes for N2 and CO molecules

The Einstein coefficients and radiative lifetimes for diatomic molecules such as N2 and CO have been computed using the Fourier Grid Hamiltonian (FGH) method and a comparison with other methods has been made. The Hamiltonian matrix is constructed using the Hulburt and Hirschfelder (HH) potential model and the Rydberg-Klein-Rees (RKR) potential model for diatomic molecules. The FGH method works well for any model of the potential including the tabulated forms of experimental potential energy data. The eigenvalues and vibrational wave-functions for the ground and the exited state of N2 and CO molecules have been computed by diagonalizing the Hamiltonian matrix. The vibrational wave-functions and eigenvalues for the ground and the excited states are used to calculate the radiative transition parameters such as Einstein coefficients (Av″v′), radiative lifetimes, electronic transition dipole moments (Re(x)), Franck–Condon factors (FCFs), r-Centroids and average internuclear separations for both the models. FGH method work well for both the models. There are good agreements between our computed values of radiative transition parameters for both the models and the values estimated by other methods.

Intensity distribution in the A1 Σ+−X1 Σ+ and A′ 1 Π−X1 Σ+ systems of barium monoxide

The integrated intensities of a few bands in the vibrational structure of the astrophysically significant A1Σ+−X1Σ+ and A′ 1Π−X1Σ+ systems of barium monoxide (BaO) have been measured experimentally using band spectra. The radiative transition parameters such as Franck-Condon (FC) factor, r-centroid, electronic transition moment, Einstein coefficient, band oscillator strength, radiative life time and effective vibrational temperature have been computed for A1Σ+−X1Σ+ and A′ 1Π−X1Σ+ systems of BaO molecule by the more reliable numerical integration procedure for the experimentally known vibrational levels using Rydberg-Klein-Rees (RKR) potential energy curves. The effective vibrational temperatures of these band systems of BaO molecule are found to be nearly 3100 °K. Hence, the radiative transition parameters help us to ascertain the presence of BaO molecule in the interstellar medium and S-stars.

Methods, algorithms, and computer codes for calculation of electron-impact excitation parameters

We describe the computer codes, developed at Vilnius University, for the calculation of electron-impact excitation cross sections, collision strengths, and excitation rates in the plane-wave Born approximation. These codes utilize the multireference atomic wavefunctions which are also adopted to calculate radiative transition parameters of complex many-electron ions. This leads to consistent data sets suitable in plasma modelling codes. Two versions of electron scattering codes are considered in the present work, both of them employing configuration interaction method for inclusion of correlation effects and Breit-Pauli approximation to account for relativistic effects. These versions difer only by one-electron radial orbitals, where the first one employs the nonrelativistic numerical radial orbitals, while the other version uses the quasirelativistic radial orbitals. The accuracy of produced results is assessed by comparing radiative transition and electron-impact excitation data for neutral hydrogen, helium, and lithium atoms as well as highly charged tungsten ions with theoretical and experimental data available from other sources.