Transition Probabilities For Forbidden Lines Research Articles

New Ritz Wavelengths and Transition Probabilities of Parity-forbidden [Mn II] Lines of Astrophysical Interest

Abstract We report a comprehensive list of accurate Ritz wavelengths and calculated transition probabilities for parity-forbidden [Mn ii] lines. Ritz wavelengths have been derived from experimentally established energy level values resulting from an extensive analysis of a high-resolution Fourier-transform emission spectrum of singly ionized manganese. Our analysis includes transitions between all known metastable and other long-lived levels of Mn ii giving a total of 1130 [Mn ii] Ritz wavelengths. Our entire list of derived Ritz wavelengths for [Mn ii] lines ranges between 237 nm and 170 μm (42,125–58 cm−1). The accurate Ritz wavelengths and calculated transition probabilities for forbidden lines in this paper are useful in the study and diagnostics of nebulae and other low-density astrophysical plasmas.

The FERRUM project: transition probabilities for forbidden lines in [Fe II] and experimental metastable lifetimes

Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [FeII] transitions that are observed as strong features in astrophysical spectra. Aims: To measure lifetimes for the 3d^6(^3G)4s a ^4G_{11/2} and 3d^6(^3D)4s b ^4D_{1/2} metastable levels in FeII and experimental transition probabilities for the forbidden transitions 3d^7 a ^4F_{7/2,9/2}- 3d^6(^3G)4s a ^4G_{11/2}. Methods: The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities. Results: The lifetimes of the a ^4G_{11/2} and the b ^4D_{1/2} levels have been measured and have the following values, 0.75(10) s and 0.54(3) s respectively. Furthermore, we have determined the transition probabilities for two forbidden transitions of a ^4F_{7/2,9/2}- a ^4G_{11/2} at 4243.97 and 4346.85 A. Both the lifetimes and the transition probabilities are compared to calculated values in the literature.

Lifetimes of metastable levels of singly ionized titanium: theory and experiment

This paper presents new theoretical lifetimes of metastable levels in singly ionized titanium, Ti II. Along with the lifetimes, transition probabilities for several decay channels from these metastable levels are presented. The calculations are supported by experimental lifetime determinations of the 3d3 b 2D5/2 and 3d2(3P)4s b 2P3/2 levels along with revised values of the previously published lifetimes of the 3d2(3P)4s b 4P5/2 and 3d2(3P)4s b 2P1/2 levels originating partly from a reanalysis utilizing a recently developed method applied on the previously recorded data and partly from new measurements. The presented theoretical investigation of lifetimes of metastable levels in Ti II shows that the HFR calculations are in general compatible with measurements performed using the ion storage ring CRYRING of Stockholm University. The transition probabilities of forbidden lines derived from the new lifetime values will be useful for the diagnostics of low density laboratory or astrophysical plasmas, particularly those encountered in the strontium filament found in the ejecta of η Carinae.

Transition probabilities of forbidden lines in Pb I

Multiconfiguration Dirac-Fock as well as semiempirical calculations of decay rates of forbidden transitions within the ground 6s26p2 configuration of neutral lead are reported and compared with relativistic Hartree-Fock results as well as with available experimental data.

The EBIT Quest for Better Transition Probabilities of Forbidden Lines

Electron beam ion traps (EBIT) lifetime measurements on forbidden lines in the visible spectrum have reached a precision of only about 5%, whereas some EBIT lifetimes measured on x-ray transitions are good to 0.5% already. Scientific and technical problems encountered when trying to improve on these limits are discussed.

Radiative transition probabilities for forbidden lines in singly ionized cobalt (Co II)

Radiative transition probabilities have been calculated for the magnetic dipole (M1) and electric quadrupole (E2) transitions connecting the 47 metastable energy levels in the 3d 8 , 3d 7 4s and 3d 6 4s 2 configurations in Co II. The most important configuration interaction (CI) and relativistic effects have been taken into account in the computations carried out with the help of the relativistic Hartree-Fock (HFR) method combined with a semi-empirical optimization of the radial parameters.

Transition probabilities for forbidden lines in Cr II

A detailed investigation of radiative transition probabilities has been performed for the magnetic dipole (M1) and electric quadrupole (E2) transitions involving the metastable energy levels within the 3d5 and 3d44s configurations of Cr II. The pseudo relativistic Hartree-Fock (HFR) method, combined with an optimization of radial parameters based on the available observed energy levels, has been used for the calculations.

Atomic data from the IRON Project. XIX. Radiative transition probabilities for forbidden lines in Fe II

Radiative transition probabilities have been calculated for the magnetic dipole (M1) and electric quadrupole (E2) transitions connecting the 63 metastable levels in the 3d 6 4s, 3d 7 and 3d 5 4s 2 configurations in Fe II. The most important configuration interaction (CI) and relativistic effects have been taken into account in the computations carried out with the help of two independent computer programs, SUPERSTRUCTURE (SST) and RELATIVISTIC HARTREE-FOCK (HFR). The results obtained in the present work are compared with previous theoretical studies and with some astrophysical observations. The new data presented here are probably the most reliable to date.

Transition probabilities for forbidden lines of Fe III

Radiative transition probabilities have been calculated for states within the 3d 6 conguration of Fe III. Magnetic dipole (M1) and electric quadrupole (E2) transition probabilities have been obtained using average energies, electrostatic and spin-orbit integrals adjusted so as to t the observed energy levels. The most important conguration interaction (CI) and relativistic eects were included explicitly in the calculations, using the relativistic Hartree-Fock (HFR) method due to Cowan. The present work represents a renement of previous monocongurational calculations of transition probabilities for forbidden lines of astrophysical interest in Fe III.

Transition probabilities for forbidden lines in the ground-state configuration of the bromine isoelectronic sequence

Calculations of transition probabilities are reported for the magnetic dipole and electric quadrupole components of the ground-state transition in the 4p5 configuration of the bromine sequence up to Xe XX. The relativistic Hartree-Fock (HFR) self-consistent-field method was used combined with parametric fitting in a configuration interaction approach. The results reported here are an extension of similar calculations recently reported in 3pN and 4pN configurations, and some comments on the effect of 3p → 4f excitations in 3p1 and 3p5 configurations are given together with a discussion of the relative merits of the HFR and HXR methods for the calculation of spin-orbit integrals.

Calculations of transition probabilities for forbidden lines in 3p N and 4p N configurations

We report on calculations of transition probabilities for M1 and E2 transitions within 3p N and 4p N configurations. We have considered a number of ions over a large range of ionization stages. The relativistic Hartree-Fock (HFR) self-consistent field method due to Cowan and Griffin was used to calculate rather extended basis sets and we have used parametric fitting in a configuration interaction approach to include the effects of more distant configurations in an approximate way. We report results for the 4 p 2 P 1 2 o − 2 P 3 2 o transitions in the Ga I isoelectronic sequence from Ga I to Xe XXIV.

Calculations of transition probabilities for forbidden lines in the 3d7 ground configurations of CO III and NI IV

Calcul des probabilites de transition du dipole magnetique et quadripole electrique pour les raies interdites de CoIII et NiIV dans les configurations 3d 7 de base

Transition probabilities of forbidden lines within the electronic configurations 6p 2 and 6p 7p of Pb I

The least squares fit of radial parameters involving radial functions of the 6p 2- and 6p 7p-configurations of Pb I has been carried out. The wave functions of the 9 lowest even levels of Pb I have been found in the basis of LSJ-states belonging to two configurations. On the base of the wave functions the transition probabilities for magnetic dipole (M1) and electric quadrupole (E2) radiation have been calculated. Comparison of experimental data and theoretical results is discussed.

Transition probabilities for forbidden lines: the silicon isoelectronic sequence from S III in to Sn XXXVII

Nouveaux calculs des probabilites de transition de toutes les raies interdites 3p 2 pour des ions alternes de S III a Sn XXXVII

Transition probabilities for forbidden lines in the 3p4 configuration – III

Radiative transition probabilities are calculated for the forbidden lines in the ground configuration 1s2 2s2 2p6 3s2 3p4 of all the members of the sulphur isoelectronic sequence up to Ni XIII. The method is based on the same elaborate procedures as those used in recent studies on the configurations 2p3, 3p3 and 3p2 by the present authors. The calculated level structure agrees with experiment to better than 6 per cent throughout the sequence, and the overall agreement between the present transition probabilities and values calculated previously by semi-empirical methods is good.

Revised Analysis of the 5p4 Ground Configuration of Two-Times Ionized Xe (Xe III) and Reevaluation of Transition Probabilities for Forbidden Lines within this Configuration

The 1S0 level in the 5p4 ground configuration of Xe III has been revised. Parameter values for the 5p4 configuration have been determined by parametric fitting and the eigenvectors used to calculate transition probabilities for magnetic dipole as well as electric quadrupole transitions within the 5p4 configuration. An improved value for the ionization potential of Xe II is used to determine the energies of the 4d105s25p4 1D2- 4d95s25p6 2D5/2 (N5O2,3O2,3 (1D2)) and 4d105s5p5 1P1-4d95s25p6 2D5/2 (N5O1O2,3 (1P1)) Auger transitions in Xe, which are commonly used as reference lines in photoelectron spectroscopy.

Transition probabilities for forbidden lines in the 2p3 configuration

Transition probabilities for forbidden lines in the 2p3 configuration

Transition probabilities for forbidden lines in the 3p3 configuration

Making use of the atomic structure computer program SUPERSTRUCTURE, radiative transition probabilities are calculated for the forbidden lines in the ground configuration |$1s^2 2s^2 2p^6 3s^2 3p^3$| of all the members of the P I isoelectronic sequence up to Ni XIV. Elaborate procedures such as configuration interaction, relativistic corrections to the magnetic dipole operator, special radial wave functions and semi-empirical term energy corrections are used in the present calculation. This leads to considerable improvements over previous work. The importance of these changes is discussed in connection with some astrophysical problems.

Measurements of transition probabilities of forbidden lines of neutral atoms and molecules

The importance of forbidden emission lines in the spectra of gaseous nebulae, aurorae, the airglow and the solar corona is emphasized together with the lack of reliable experimental lifetime measurements for most of these transitions. Several methods for forbidden lifetime measurements of neutral atoms and molecules are discussed and details given of the pulsed stationary afterglow and the thermal beam time-of-light techniques. Results of lifetime measurements on metastable levels of helium, atomic oxygen, carbon monoxide and molecular nitrogen which decay by forbidden transitions are discussed.

Atomic Transition Probabilities for Forbidden Lines of the Iron Group Elements: (A Critical Data Compilation for Selected Lines)

Atomic transition probabilities for about 750 forbidden spectral lines for elements of the iron group, specifically V, Cr, Mn, Fe, Co, and Ni, have been critically evaluated and compiled using all available literature sources. The selection of the spectra and elements has been made primarily according to their astrophysical importance. The data are presented in separate tables for each element and stage of ionization, and for each ion the data are arranged according to multiplets. For each line within a multiplet the transition probability for spontaneous emission is listed along with the standard spectroscopic designation, the wavelength, the statistical weights, and the energy levels of the upper and lower states. In addition, the estimated accuracy and the source are indicated. In short introductions which precede the individual tables for the ions the main justifications for the choice of the adopted data and for the accuracy rating are discussed. A general introduction contains a detailed discussion of the critical factors entering into the calculations. It also includes detailed comparisons of calculated data with astrophysical observations and a few laboratory results, which serve as a valuable indication for the validity of the estimated accuracies.