Odd-parity Levels Research Articles

Two-photon Doppler-free ultraviolet laser spectroscopy on sulphur atoms

The 3p43PJ–3p34p3PJ transition in the sulphur atom is investigated in a precision two-photon excitation scheme under Doppler-free and collision-free circumstances yielding an absolute accuracy of 0.0009 cm−1, using a narrowband pulsed laser. This verifies and improves the level separations between amply studied odd parity levels with even parity levels in S I. An improved value for the 3P2–3P1 ground state fine structure splitting is determined at 396.0564 (7) cm−1. A 34S–32S atomic isotope shift was measured from combining time-of-flight mass spectrometry with laser spectroscopy.

Hyperfine structure studies of the electronic levels of the manganese atom. II. Odd-parity level system

The hyperfine structure of 15 spectral lines of the manganese atom was investigated with the method of laser induced fluorescence on an atomic beam. Results of these investigations, supplemented by the results obtained in Part I of this work series, yielded the hyperfine structure constants A and B for altogether 38 odd-parity levels. For 11 levels the A and B values are reported for the first time, for another 10 levels new constants B were evaluated, and for the remaining 17 levels the accuracy of the hitherto available literature data was improved; thus the available database of the hyperfine structure constants for the manganese atom was considerably extended. A semi-empirical fit of the fine and the hyperfine structure for the odd-parity level system of the atomic manganese was also performed in the present work; generally a good agreement between the experimental and the calculated values was found.

Systematic investigations of the hyperfine structure constants of niobium I levels. Part III: High lying even parity levels (37,410–43,420 cm−1) and discovery of a new level

The present work is the third part of a systematic investigation of the hyperfine structure of atomic Niobium using laser induced fluorescence spectroscopy. As in the previous two parts, spectral lines in the wavelength region between 5540 and 6570 Å were investigated. In the present part we report on 31 transitions between lower odd parity levels and high-lying even parity levels between 37,410 and 43,420 cm−1. 15 of these 31 lines were already known emission lines, the transition wavelengths of the other 16 lines were calculated as combinations between known energy levels. The constants of the involved levels could be determined, in most cases, with lower uncertainty compared to literature values. For some levels we had to use also results from an analysis of Fourier-transform spectra. The discovery of a previously unknown energy level, 32,361.11 cm−1, even parity, J = 5/2, is also reported.

Systematic investigations of the hyperfine structure constants of niobium I levels. Part I: Constants of upper odd parity energy levels between 16,672 and 31,025 cm−1 and discovery of a new level

In the wavelength region between 5540 and 6570 Å systematic laser spectroscopic studies of the hyperfine (hf) structure of Niobium I - lines were performed, detecting laser-induced fluorescence signals. Possible transition wavelengths were calculated as combinations between all known energy levels. Altogether about 380 transitions could be successfully excited and their hyperfine structure could be investigated. This large manifold of lines allowed us to evaluate our results via multiple transitions between the system of upper and lower energy levels. In Part I we report on transitions between lower even parity levels between 0 and 13,515 cm-1 and upper odd parity levels between 16,672 and 31,025 cm−1. Most of the hyperfine structure constants of the involved levels could be determined with lower uncertainty compared to literature values. The discovery of a previously unknown energy level, 27,994.38 cm−1, odd parity, J = 1/2, is also reported.

Systematic investigations of the hyperfine structure constants of niobium I levels. Part II: Constants of upper odd parity energy levels between 31,056 and 42,000 cm−1 and discovery of two new levels

The present paper is the continuation of the systematic investigation of the hyperfine (hf) structure of atomic Niobium presented in Part I of this work. Just like in Part I, spectral lines in the wavelength region between 5540 and 6570 Å were investigated by laser-induced fluorescence spectroscopy. From altogether about 380 transitions, about 190 are treated in this part. Here, we report on transitions between lower even parity levels between 13,515 and 23,048 cm-1 and upper odd parity levels between 31,025 and 42,000 cm−1. Most of the hyperfine structure constants of the involved levels could be determined with lower uncertainty compared to literature values. Additionally, the discovery of two previously unknown energy levels is reported: one level of even parity at 21,182.31 cm−1, J = 5/2, as well as one level of odd parity at 39,834.88 cm−1, J = 13/2.

Laser spectroscopic investigation of atomic holmium in the wavelength range from 780 nm to 830 nm: Hyperfine structure measurements and a new energy level

The hyperfine structure of neutral holmium was studied using a hollow cathode discharge lamp and laser-induced fluorescence spectroscopy or optogalvanic spectroscopy, respectively. Altogether 42 spectral lines in the wavelength range from 780 nm to 830 nm were investigated. Magnetic dipole hyperfine structure constants A and electric quadrupole hyperfine structure constants B were determined for 23 levels of even parity and for 25 levels of odd parity. Eight of the reported hyperfine structure constants have not been published before. For most other levels, previously published hyperfine structure constants have been measured with greater precision. Additionally, one new energy level 29013.43 cm−1 with odd parity and J=13/2 has been discovered.

Fine- and hyperfine structure investigations of the odd-parity configuration system in atomic holmium

In this work a parametric study of the fine (fs) and the hyperfine structure (hfs) for the odd-parity level system in the holmium atom (Ho I) is presented. A large amount of new experimental data, published in the last three years, have been considered for the fs and hfs semi-empirical analysis. Multiconfiguration calculations, both for the fine and the hyperfine structure, for 11 configurations with all the 4fN core states, by taking into account the second-order of perturbation theory, have been performed for the first time. Predicted values of level energies as well as magnetic dipole and electric quadrupole A and B hfs constants are listed. These values are of special interest if no experimental values are available. Some important information concerning the electronic structure of the holmium atom for further calculations of elements with open 4f electronic shell has been achieved.

Hyperfine structure studies of the odd-parity electronic levels of the terbium atom

In this work the hyperfine structure of 43 odd-parity levels of the terbium atom was investigated with the method of laser induced fluorescence in a hollow cathode discharge. Altogether 73 spectral lines were examined, with the odd-parity levels involved as the upper levels. For 41 levels the constants A and B were determined for the first time, and for the remaining two levels improved values could be obtained due to the supplementary measurements performed. As a by-product, also the hyperfine structure constants for two lower even-parity levels could be corrected. The obtained results concerning the odd-parity levels contributed to considerable extension of the available database of the hyperfine structure constants for the atomic terbium; they would be included in the semi-empirical analysis of the fine and the hyperfine structure for the odd-parity configurations system, planned in our research group.

Atomic Transition Probabilities for UV and Blue Lines of Fe ii and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937

Abstract We report new branching fractions (BFs) for 121 UV lines from the low-lying odd-parity levels of Fe ii belonging to the z6Do, z6Fo, z6Po, z4Fo, z4Do, and z4Po terms of the 3d6(5D)4p configuration. These lines range in wavelength from 2250 to 3280 Å and originate in levels ranging in energy from 38,459 to 47,626 cm−1. In addition, we report BFs for 10 weak blue lines connecting to the z4Do term that range in wavelength from 4173 to 4584 Å. The BFs are combined with radiative lifetimes from the literature to determine transition probabilities and log(gf) values. Comparison is made to selected experimental and theoretical data from the literature. Our new data are applied to iron abundance determinations in the Sun and in metal-poor star HD 84937. For the Sun, eight blue lines yield log ε(Fe) = 7.46 ± 0.03, in agreement with standard solar abundance estimates. For HD 84937 the observable wavelength range extends to the vacuum UV (λ ≥ 2327 Å), and from 75 lines we derive log ε(Fe) = 5.26 ± 0.01 (σ = 0.07), near to the metallicity estimates of past HD 84937 studies.

Hyperfine structure studies of the odd-parity electronic levels in the holmium atom. II: New levels

This work is devoted to investigations of unclassified spectral lines in atomic holmium, aiming at identification of new electronic levels and determination of their hyperfine structure. Altogether 113 unclassified lines were investigated with the method of laser induced fluorescence in a hollow cathode discharge lamp. As a result, 35 odd-parity electronic levels with previously unknown energies were identified; for all of them the hyperfine structure constants A and B were also determined. The data reported greatly facilitated the semi-empirical fit of the fine and hyperfine structure of the odd-parity level system, performed in our group.

Experimental and Theoretical Radiative Lifetimes, Branching Fractions, Transition Probabilities, and Oscillator Strengths of Nb i Levels

Abstract Radiative lifetimes for 60 odd-parity levels of Nb i belonging to the 4d35s5p and 4d45p configurations, except for two levels with unknown configuration, which are in the energy range between 23,910.90 and 37,188.28 cm−1, are measured by the time-resolved laser-induced fluorescence technique. The lifetime values range from 7.1 to 118.7 ns with uncertainties less than 10%. To our knowledge, 45 lifetime values determined in this paper are reported for the first time. By combining the experimental lifetimes with measured or computed branching fractions, we obtain transition probabilities and oscillator strengths for the individual channels depopulating the investigated levels.

Hyperfine structure studies of the odd-parity electronic levels of the holmium atom. I: Levels with known energies

In this work investigations of the hyperfine structure of 66 spectral lines of the holmium atom were performed with the method of laser induced fluorescence in a hollow cathode discharge lamp. Altogether 43 odd-parity levels, involved as the upper levels in the transitions studied, were investigated. For about half of them the hfs constants A and B were evaluated for the first time. For some levels, already examined in earlier works, supplementary results were obtained; for a few levels it was possible to compare our results with earlier literature data. For 4 levels J quantum numbers were changed with respect to the available literature values. As a by-product, also improved hfs constants for the lower even-parity levels were determined. The data reported facilitated the semi-empirical fit of the fine and hyperfine structure of the odd-parity level system, performed in our group.

Second spectrum of Manganese (Mn II), Part II: Revised fine and hyperfine structure analysis of odd-parity levels

In the first part of this global work, we have achieved the fine and hyperfine structure (fs and hfs) parametric study of even-parity levels, which confirmed in the whole the well-founded basis of previous analyses. Unfortunately, in the present work devoted to odd-parity levels, some divergences appear. For instance, the three levels w5P3, w5P2, w5P1 located respectively at 86898, 86937 and 86961 cm−1 should not belong to the 3d4(5D)4s4p configuration, as indicated earlier, but rather to 3d5(4P)5p. In the other hand, the levels whose energies are: 88840, 89079 and 89429 cm−1 should belong this time to 3d4(5D)4s4p instead of 3d55p, as mentioned previously. Our analysis is strengthened when using experimental hfs data as finger prints, even if the comparison between these experimental hfs data, given in the literature, and our calculated results also shows in numerous cases some notable discrepancies, concerning particularly the sign of the electric quadrupole factor. The main monoelectronic hfs parameter values, extracted from our least square fitting procedure, are: a3d01(3d54p)= 17.58 mK, b3d02(3d54p)= 10.27 mK, a3d01 (3d44s4p)= 18.74 mK and a4s10(3d44s4p)= 274.9 mK. These parameter values, displayed for the first time, were analyzed and compared with ab-initio calculations. As in the first part, we conclude this work by giving the predicted hfs A and B constants of low-lying levels of these two configurations, whose splitting are not yet measured.

Experimental radiative lifetimes, branching fractions, transition probabilities and oscillator strengths of some levels in Au I

Radiative lifetimes of ten odd-parity levels in neutral gold were measured by time-resolved laser-induced fluorescence method, and six of them were reported for the first time. Branching fractions (BFs) of 15 lines for eight of these levels were determined by the emission spectrum of a hollow cathode lamp. The transition probabilities and oscillator strengths of these lines were derived by combining the BFs with lifetime values. The lifetime and oscillator strength results are in very good agreement with previous data.

Experimental and Theoretical Radiative Lifetimes, Branching Fractions, Transition Probabilities, and Oscillator Strengths of Some Highly Excited Odd-parity Levels in Ir i

Abstract Radiative lifetimes of 62 odd-parity levels of Ir i in the energy range between 32513.43 and 58625.10 cm−1 were measured using the time-resolved laser-induced fluorescence technique. The lifetime values obtained are in the range from 3.2 to 345 ns. To our best knowledge, 59 results are reported for the first time. These are compared to computed data deduced from a pseudo-relativistic Hartree–Fock model including core-polarization contributions. From the combination of the experimental lifetime measurements and branching fraction calculations, a new set of transition probabilities and oscillator strengths is derived for 134 Ir i spectral lines of astrophysical interest in the wavelength region from 205 to 418 nm.

Identification of new electronic levels in the holmium atom and investigation of their hyperfine structure

In this work the hyperfine structure of some tens of unclassified spectral lines in the holmium atom was investigated with the method of laser induced fluorescence in a hollow cathode discharge lamp. As a result, 21 new electronic odd-parity levels, with previously unknown energies within the range 33000–42000 cm−1, were identified and their hyperfine structure constants A and B were determined. The experimental data obtained will facilitate the semi-empirical fit of the fine and hyperfine structure of the odd-parity level system for the atomic holmium, currently in progress in our group.

Lande gJ factors for even-parity electronic levels in the holmium atom

In this work the hyperfine structure of the Zeeman splitting for 18 even-parity levels in the holmium atom was investigated. The experimental method applied was laser induced fluorescence in a hollow cathode discharge lamp. 20 spectral lines were investigated involving odd-parity levels from the ground multiplet, for which Lande gJ factors are known with high precision, as the lower levels; this greatly facilitated the evaluation of gJ factors for the upper levels. The gJ values for the even-parity levels considered are reported for the first time. They proved to compare fairly well with the values obtained recently in a semi-empirical analysis for the even-parity level system of Ho I.

Fine- and hyperfine structure investigations of the even-parity configuration system of the atomic holmium

In this work new experimental results concerning the hyperfine structure (hfs) for the even-parity level system of the holmium atom (Ho I) were obtained; additionally, hfs data obtained recently as a by-product in investigations of the odd-parity level system were summarized. In the present work the values of the magnetic dipole and the electric quadrupole hfs constants A and B were determined for 24 even-parity levels, for 14 of them for the first time. On the basis of these results, as well as on available literature data, a parametric study of the fine structure and the hyperfine structure for the even-parity configurations of atomic holmium was performed. A multi-configuration fit of 7 configurations was carried out, taking into account second-order of the perturbation theory. For unknown electronic levels predicted values of the level energies and hfs constants are given, which can facilitate further experimental investigations.

Hyperfine structure investigations for the odd-parity configuration system in atomic holmium

In this work new experimental results of the hyperfine structure (hfs) in the holmium atom are reported, concerning the odd-parity level system. Investigations were performed by the method of laser induced fluorescence in a hollow cathode discharge lamp on 97 spectral lines in the visible part of the spectrum. Hyperfine structure constants: magnetic dipole - A and electric quadrupole - B for 40 levels were determined for the first time; for another 21 levels the hfs constants available in the literature were remeasured. Results for the A constants can be viewed as fully reliable; for B constants further possibilities of improving the accuracy are considered.

Fe i Oscillator Strengths for Transitions from High-lying Odd-parity Levels

Abstract We report new experimental Fe i oscillator strengths obtained by combining measurements of branching fractions measured with a Fourier Transform spectrometer and time-resolved, laser-induced fluorescence lifetimes. This study covers the spectral region ranging from 213 to 1033 nm. A total of 120 experimental -values coming from 15 odd-parity energy levels are provided, 22 of which have not been reported previously and 63 of which have values with lower uncertainty than the existing data. The radiative lifetimes for 60 upper energy levels are presented, 39 of which have no previous measurements.