Magnetic Hyperfine Structure Research Articles

Hyperfine Structure Investigation of Singly Ionized Thulium in Fourier-transform Spectra

The hyperfine structure of 40 spectral lines of singly ionized thulium (Tm ii) in emission spectra from a hollow cathode discharge lamp measured with a Fourier transform spectrometer in the wavelength range from 335 to 2345 nm has been investigated. As a result of the analysis, the magnetic dipole hyperfine structure constants A for 27 fine structure levels of Tm ii were determined for the first time. In addition, the values of two magnetic dipole hyperfine structure constants A from the literature were declared incorrect, and the corrected values were given.

Variation of the Quadrupole Hyperfine Structure and Nuclear Radius due to an Interaction with Scalar and Axion Dark Matter.

Atomic spectroscopy is used to search for the space-time variation of fundamental constants which may be due to an interaction with scalar and pseudoscalar (axion) dark matter. In this Letter, we study the effects that are produced by the variation of the nuclear radius and electric quadrupole moment. The sensitivity of the electric quadrupole hyperfine structure to both the variation of the quark mass and the effects of dark matter exceeds that of the magnetic hyperfine structure by 1-2 orders of magnitude. Therefore, the measurement of the variation of the ratio of the electric quadrupole and magnetic dipole hyperfine constants is proposed. The sensitivity of the optical clock transitions in the Yb^{+} ion to the variation of the nuclear radius allows us to extract, from experimental data, limits on the variation of the hadron and quark masses, the QCD parameter θ and the interaction with axion dark matter.

Hyperfine structure and isotope shift of neutral and singly ionized europium by Fourier transform spectroscopy

The magnetic dipole hyperfine structure (HFS) constants A of neutral and singly ionized europium (Eu I and Eu II) were determined using the emission spectra recorded by the Fourier transform spectrometer at the National Solar Observatory (NSO) at the Kitt Peak, USA. The HFS constants of 29 levels of Eu I and 15 levels of Eu II were determined, from which 22 results for Eu I and 8 results for Eu II are reported for the first time, as far as we know. The isotope shifts (ISs) of 30 transitions of Eu I and 19 transitions of Eu II were also determined, and the ISs of 22 transitions of Eu I and 8 transitions of Eu II are reported for the first time. This work increases the total number of levels with experimentally determined HFS constants A to 202 for Eu I and 24 for Eu II, and increases the number of transitions with known ISs to 359 for Eu I and 36 for Eu II.

New even parity fine structure energy levels of atomic vanadium

Four new fine structure energy levels of atomic vanadium have been discovered for the first time. Experiments were carried out with laser-induced fluorescence spectroscopy and optogalvanic spectroscopy using tunable continuous wave lasers in the wavelength ranges between 750 nm and 850 nm and between 590 nm and 650 nm, respectively. The new levels, all lying in the 42 400 to 49 940 cm−1 energy range, were each experimentally confirmed by two or more observed transitions involving previously known energy levels. Accurate energy level values were found using lines measured by Fourier transform spectroscopy. The values for the total angular momentum quantum numbers J of the new levels were found by the analysis of the hyperfine structure of the spectral lines investigated. Magnetic dipole hyperfine structure constants A for all new levels were determined. Additionally, for one previously known energy level the magnetic dipole hyperfine structure constant A from the literature was corrected.

Calculation of the hyperfine structure of Dy, Ho, Cf, and Es

A recently developed version of the configuration interaction (CI) method for open shells with a large number of valence electrons has been used to study two heavy atoms, californium (Cf, Z= 98) and einsteinium (Es, Z= 99). Motivated by experimental work to measure the hyperfine structure (HFS) for these atoms, we perform the calculations of the magnetic dipole HFS constants $A$ and electric quadrupole HFS constant $B$ for the sake of interpretation of the measurements in terms of nuclear magnetic moment $\mu$ and electric quadrupole moment $Q$. For verification of our computations, we have also carried out similar calculations for the lighter homologs dysprosium (Dy, Z= 66) and holmium (Ho, Z= 67), whose electronic structures are similar to Cf and Es, respectively. We have conducted a revision of the nuclear moments of some isotopes of Es leading to an improved value of the magnetic moment of $^{253}$Es [$\mu$($^{253}$Es) = 4.20(13)$\mu_N$].

Bohr-Weisskopf effect in the potassium isotopes

The magnetic hyperfine structure constants have been calculated for low-lying levels in neutral potassium atom taking into account the Bohr--Weisskopf (BW) and Breit--Rosenthal (BR) effects. According to our results the $4p_{1/2}$ state of K~I is free from both BR and BW corrections on the level of the current theoretical uncertainties. Using this finding and the measured values of the $A(4p_{1/2})$ constants, we corrected the nuclear magnetic moments for several short-lived potassium isotopes. The BW correction is represented as a product of atomic and nuclear factors. We calculated the atomic factor for the ground state of K I, which allowed us to extract nuclear factors for potassium $I^\pi = 3/2^+$ isotopes from the experimental data. In this way the application range of the single-particle nuclear model for nuclear-factor calculation in these isotopes has been clarified.

Nontrivial Shapes of the Mössbauer Spectra of Magnetic Nanoparticles with Different Forms of Magnetic Anisotropy

The continual and quantum-mechanical models of magnetic dynamics are considered for a system of ferromagnetic nanoparticles with different forms of magnetic anisotropy alongside with the corresponding theory for describing the Mössbauer spectra of such materials. The calculations of spectra in these models demonstrate various forms of the magnetic hyperfine structure upon the evolution of the absorption spectra of nanoparticles from a well-resolved magnetic hyperfine structure (sextet of lines for 57Fe nuclei) at low tem-peratures to a single line or a five-stage pedestal at high temperatures. These models substantially broaden the methodological basis for the diagnostics of magnetic nanomaterials by the method of Mössbauer spec-troscopy.

Theoretical investigations of electronic spectra of silver atom using all-electron scalar relativistic basis

Exploration of the tractable size basis set that can provide reliable estimates of computed properties for systems containing heavy elements has been the subject of interest in quantum chemistry over many decades. In this connection, the recently developed segmented all-electron relativistically contracted (SARC) basis set proposed by Rolfes et al. [J. Comput. Chem. 41, 1842 (2020)] appears to be worth studying. In the present attempt, ground and excited state properties of the Ag atom is computed on this basis at the Fock-space multi-reference coupled cluster (FSMRCC) level of theory with four-component relativistic spinors. The computed quantities resulting from the SARC basis are subsequently compared with those obtained using an even-tempered basis to assess the efficacy of the SARC basis. Computations have also been performed with the extended SARC basis to improve the quality of the property of interest. The accuracy of the computed quantities such ionization energy, electron affinity, excitation energies, etc., obtained using the SARC basis at the FSMRCC level of theory demonstrates that the SARC basis (particularly the extended one), which is primarily designed for quantum chemical calculations at the two-component scalar relativistic level for systems containing heavy atoms, can be used for fully relativistic calculations. The magnetic dipole hyperfine structure constant A, oscillator strengths f and transition rates Afi calculated using the SARC basis also agree well with the experiment and with the available theoretical estimates.

Hyperfine structure and isotope shift for neutral and singly ionized rhenium using Fourier transform spectroscopy

The hyperfine structure (HFS) constants of 80 levels in Re I and three levels in Re II were measured by fitting Fourier transform spectra. Simultaneously, the isotope shifts (IS) of 161 transitions of Re I and four transitions of Re II were also determined. By combining these IS results and the level IS values known from literatures, the IS values of 80 levels in Re I and three levels in Re II were determined. To our best knowledge, the HFS constants of 73 levels and the ISs of 154 transitions in Re I, and the HFS constants of three levels and the ISs of four transitions in Re II are reported for the first time. Our results have good agreements with the previous results. This study extended the total number of the magnetic dipole HFS constant A to 117 for Re I and seven for Re II, and increased the number of transitions with known ISs to 214 for Re I and seven for Re II. These data are greatly helpful for more accurate insights into atomic structure at hyperfine level.

Comment on: “Hyperfine structure measurements of Co I and Co II with Fourier transform spectroscopy” by Fu et al. [JQSRT 2021, 107590

This comment points out errors in the analysis of 61 magnetic hyperfine structure (A) constants of Co II energy levels by Fu et al. [JQSRT 2021, 107590]. The paper was published without full awareness of the extensive literature already available for Co II hyperfine A constants at the time; 57 of 58 A constants that were claimed to have been measured for the first time had already been measured by the prior work of Ding and Pickering [ApJS 2020, 251:24], who had published A constants for 292 levels of Co II. The A constant of 3d64s2 a5D4 has been determined by Fu et al. [JQSRT 2021, 107590] for the first time to be 12.0±1.8 mK (1 mK = 0.001 cm−1), which was found to agree with line profiles observed by Ding and Pickering [ApJS 2020, 251:24]. Discrepancies in 17 A constants of Fu et al. [JQSRT 2021, 107590] were found, which are likely due to the analysis of weak, experimentally unclassified transitions with Ritz wavenumbers 25453.966 cm−1 and 25149.948 cm−1 by Fu et al. [JQSRT 2021, 107590] for the A constants of the energy levels 3d7(2G)4s a3G5 and 3d7(2P)4s c3P2 respectively. Fewer transitions and poorer quality spectra analysed by Fu et al. [JQSRT 2021, 107590] are also concluded to have contributed to disagreements in the 17 A constants.

Experimental investigation of the hyperfine structure of Tm I with Fourier transform spectroscopy, part A: In the visible wavelength range (400–700 nm)

The spectra emitted by a thulium hollow-cathode discharge lamp with argon or neon as inert gases have been recorded with a Bruker IFS 125 HR fourier transform spectrometer in the visible wavelength region from 400 to 700 nm. The paper presents the investigation of the hyperfine-structure splitting of 50 spectral lines of neutral thulium. As a result, the magnetic dipole hyperfine structure constant A for 20 fine structure levels of Tm I have been determined for the first time.

Hyperfine structure constants for neutral and singly ionized vanadium by Fourier transform spectroscopy data

The hyperfine structure (HFS) for V I and V II were investigated using the archival data recorded by the Fourier transform spectrometer (FTS) at the US National Solar Observatory (NSO) with a fitting program written by us. The magnetic dipole HFS constant A values for 53 levels of V I between 0 and 52,948 cm−1 and for 56 levels of V II between 36 and 72,952 cm−1 are obtained, of which 46 results for V I and 50 results for V II are reported for the first time, as far as we know. And to our knowledge, so far, the A constants of 370 levels of V I and 76 levels of V II have been measured in literature. The new results obtained in this work supplement more experimental HFS data very useful in astrophysics and atomic physics etc..

Релаксационный процесс магнитных моментов в инварных сплавах, легированных хромом

Invar alloys Ni31(Fe69-x Crx), х = 3,4,6 and 8 (at.%) in the temperature range 120-400 K have been studied by magnetic and Mössbauer methods. It is find out the absence of a magnetic hyperfine structure of 57Fe nuclei in the magnetically ordered temperature range for alloys with x= 6 and 8. The magnetic structure of the alloys can be represented as a system of superparamagnetic clusters, the magnetic moments of which relax between differently populated energy levels. The phenomenon is explained by the increased frequency of relaxation of magnetic moments between these levels.

Relaxation process of magnetic moments in chromium-doped Invar alloys

Invar alloys Ni31(Fe69-xCrx) x=3, 4, 6 and 8 (at.%) in the temperature range 120-400 K have been studied by magnetic and Messbauer methods. It is find out the absence of a magnetic hyperfine structure of 57Fe nuclei in the magnetically ordered temperature range for alloys with x=6 and 8. The magnetic structure of the alloys can be represented as a system of superparamagnetic clusters, the magnetic moments of which relax between differently populated energy levels. The phenomenon is explained by the increased frequency of relaxation of magnetic moments between these levels. Keywords: invar alloy, magnetization, Curie temperature, magnetic moment, relaxation process, Messbauer effect.

Prediction of optical polarization and high-field hyperfine structure via a parametrized crystal-field model for low-symmetry centers in Er3+ -doped Y2SiO5

We report on the development and application of a parametrized crystal-field model for both ${\mathrm{C}}_{1}$ symmetry centers in trivalent erbium-doped ${\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$. High-resolution Zeeman and temperature dependent absorption spectroscopy was performed to acquire the necessary experimental data. The obtained data, in addition to the ground $(^{4}\mathrm{I}_{15/2}{\mathrm{Z}}_{1})$ state and exited $(^{4}\mathrm{I}_{13/2}{\mathrm{Y}}_{1})$ state Zeeman and hyperfine structure, were simultaneously fitted in order to refine an existing crystal-field interpretation of the ${\mathrm{Er}}^{3+}$:${\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ system. We demonstrate that it is possible to account for the electronic, magnetic, and hyperfine structure of the full $4{f}^{11}$ configuration of ${\mathrm{Er}}^{3+}$:${\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ and further, that it is possible to predict both optical polarization behavior and high magnetic field hyperfine structure of transitions in the $1.5\text{\ensuremath{-}}\ensuremath{\mu}\mathrm{m}$ telecommunications band.

Hyperfine structure measurements of Nb I and Nb II by Fourier transform spectroscopy

Some of the archival data derived from the Fourier transform spectrometer (FTS) at the US National Solar Observatory ranging from 0 − 36,947 cm−1 were investigated to study the hyperfine structure (HFS) patterns of Nb I and Nb II lines. The analysis of 155 lines in the FTS spectra was performed by a least squares fitting to derive values of the magnetic dipole HFS constant A. In total, the HFS constant A was determined for 68 levels of Nb I between 11,524.65 and 45,719.07 cm−1 and for 57 levels of Nb II between 2356.816 and 73,869.773 cm−1. 26 results for Nb I and 46 results for Nb II are reported for the first time, as far as we know.

Effect of nuclear magnetization distribution within the Woods-Saxon model: Hyperfine splitting in neutral Tl

Three models of the nuclear magnetization distribution are applied to predict the hyperfine structure of the hydrogenlike heavy ions and neutral thallium atoms: the uniformly magnetized ball model and single-particle models for the valence nucleon with the uniform distribution and the distribution determined by the Woods-Saxon potential. Results for the hydrogenlike ions are in excellent agreement with previous studies. The application of the Woods-Saxon model is now extended to the neutral systems with the explicit treatment of the electron correlation effects within the relativistic coupled cluster theory using the Dirac-Coulomb Hamiltonian. We estimate the uncertainty for the ratio of magnetic anomalies and numerically confirm its near nuclear-model independence. The ratio is used as a theoretical input to predict the nuclear magnetic moments of short-lived thallium isotopes. We also show that the differential magnetic anomalies are strongly model dependent. The accuracy of the single-particle models significantly surpasses the accuracy of the simplest uniformly magnetized ball model for the prediction of this quantity. Skripnikov [Skripnikov, J. Chem. Phys. 153, 114114 (2020)] has shown that the Bohr-Weisskopf contribution to the magnetic dipole hyperfine structure constant for an atom or a molecule induced by a heavy nucleus can be factorized into the electronic part and the universal nuclear magnetization dependent part. We numerically confirm this factorization for the Woods-Saxon single-particle model with an uncertainty less than 1%.

Atomic calculations of the hyperfine-structure anomaly in gold

The magnetic hyperfine structure constants have been calculated for low-lying levels in neutral gold atom and gold-like ion of mercury taking into account Bohr--Weisskopf (BW) effect. BW effect is represented as a product of atomic and nuclear ($d_\mathrm{nuc}$) factors. We have calculated the atomic factors, which enable one to extract BW-correction values for far from stability gold nuclei from the experimental data. The possible uncertainty of our atomic calculations have been estimated by the comparison with the available experimental data. It has been shown that the standard single-particle approach in $d_\mathrm{nuc}$ calculation reasonably well describes experimental data for $11/2^-$ gold isomers and $3/2^+$ ground state of $\rm ^{199}Au$. At the same time, it fails to describe the hyperfine constant in $^{197}\mathrm{Au}$. This indicates the more pronounced configuration mixing in $\rm ^{197}Au$ than in $\rm ^{199}Au$.

Discovery of new even-parity fine structure levels of Pr I with angular momenta 1/2, 3/2, and 5/2

The spectrum of Praseodymium was investigated in the visible region from 4000 Å to 7500 Å based on previously recorded Fourier Transform spectra. Source of free Pr atoms was a hollow cathode discharge lamp. The investigation of spectral lines was performed using laser-induced fluorescence spectroscopy. A tunable single mode ring-dye laser, pumped by a frequency doubled Nd-YAG laser, was used as the light source to investigate selected lines. Hyperfine spectra of 129 lines were recorded and the magnetic dipole hyperfine structure constants of the involved energy levels were determined. This led to the discovery of up to now unknown levels. In this paper, 30 even parity levels, having J-values of 1/2, 3/2, and 5/2 are presented. The existence of all levels is confirmed by several laser excitations in the spectral range of our dye laser.

Semi-empirical determination of the nuclear quadrupole moment of ^{109}Sn

The nuclear quadrupole moment (Q) of ^{109}Sn was determined by means of hyperfine structure (hfs) many-body parametrization method. The hyperfine structure splittings for isotopes ^{117-131}Sn recently measured by Yordanov et al. (Commun Phys 3:1, 2020) were used in multiconfiguration semi-empirical calculations. The contributions from the second-order perturbation theory to the magnetic dipole hyperfine structure, concerning electrostatically correlated hyperfine interactions, were taken into consideration for even and odd configurations simultaneously. Contributions from the second-order perturbation theory to the electric quadrupole hyperfine structure, concerning spin–orbit correlated hyperfine interactions, were included for the first time.