Natalia S. Oreshkina

Nuclear Shape Effect on the g Factor of Hydrogenlike Ions

The nuclear shape correction to the g factor of a bound electron in the 1S state is calculated for a number of nuclei in the range of charge numbers from Z=6 up to Z=92. The leading relativistic deformation correction has been derived analytically, and also its influence on one-loop quantum electrodynamic terms has been evaluated. We show the leading corrections to become significant for mid-Z ions and for very heavy elements to even reach the 10(-6) level.

Astrophysical line diagnosis requires non-linear dynamical atomic modeling

Line intensities and oscillator strengths for the controversial 3C and 3D astrophysically relevant lines in neonlike Fe(16+) ions are calculated. A large-scale configuration-interaction calculation of oscillator strengths is performed with the inclusion of higher-order electron-correlation effects, suggesting that these contributions cannot explain existing discrepancies between theory and experiment. Then, we investigate nonlinear dynamical effects, showing that, for strong x-ray sources, the modeling of the spectral lines by a peak with an area proportional to the oscillator strength is not sufficient. The dynamical effects give a possible resolution of discrepancies of theory and experiment found by recent measurements, which motivates the use of light-matter interaction models also valid for strong light fields in the analysis and interpretation of astrophysical and laboratory spectra.

Coronium in the Laboratory: Measuring the Fe XIV Green Coronal Line by Laser Spectroscopy

The green coronal line at 530.3 nm was first observed during the total solar eclipse of 1869. Once identified as emitted by Fe XIV, it became clear that this highly charged ion was typical for the range of temperatures found in coronal plasmas, stellar winds, outflows, and accretion disks. Under these conditions of high ionization, the strongest transitions are in the X-ray, extreme ultraviolet, and ultraviolet wavelength range, with only few optical lines. For these so-called forbidden coronal lines, only scarce laboratory data is available, and even advanced atomic theory codes cannot yet predict their wavelengths with the accuracy required for precise absolute velocity determinations of such plasmas. Here we report on a study of the Fe XIV line, a key coronal transition of a highly charged ion, using laser spectroscopy in an electron beam ion trap, obtaining the first laboratory measurement of 530.2801(4) nm for its rest wavelength. The result enables the determination of absolute line shifts and line broadenings in hot turbulent plasmas and astrophysical environments, with an error bar of only 0.24 km s–1. In addition, our measurement provides a much-needed benchmark for advanced atomic structure calculations, which are fundamental for astronomy.

Identifications of and EUV transitions of promethium-like Pt, Ir, Os and Re

We investigated Pm-, Nd-, and Pr-like spectra in the extreme ultra-violet region around 20 nm of Pt, Ir, Os, and Re (Z = 78–75) produced in the Heidelberg electron beam ion trap. Identification of the transitions was supported by several theoretical calculations, including collisional radiative modeling of the observed spectra. Special attention is given to the identifications of the alkaline-like – resonance lines in promethium-like highly charged ions. Previous identifications of these lines have been tentative at best due to disagreements with theory and doubts about the experimental charge state identifications. Our experimental results for the – wavelengths are accurate at the 0.005%-level. Understanding the level-structure of ions near the – level crossing is of particular importance for future searches of a possible fine-structure constant variation, and new optical clocks.

Identifications of 5s1/2−5p3/2 and 5s2−5s5p EUV transitions of promethium-like Pt, Ir, Os and Re

We investigated Pm-, Nd-, and Pr-like spectra in the extreme ultra-violet region around 20 nm of Pt, Ir, Os, and Re (Z = 78–75) produced in the Heidelberg electron beam ion trap. Identification of the transitions was supported by several theoretical calculations, including collisional radiative modeling of the observed spectra. Special attention is given to the identifications of the alkaline-like – resonance lines in promethium-like highly charged ions. Previous identifications of these lines have been tentative at best due to disagreements with theory and doubts about the experimental charge state identifications. Our experimental results for the – wavelengths are accurate at the 0.005%-level. Understanding the level-structure of ions near the – level crossing is of particular importance for future searches of a possible fine-structure constant variation, and new optical clocks.

Theoretical prediction of the fine and hyperfine structure of heavy muonic atoms

Precision calculations of the fine and hyperfine structure of muonic atoms are performed in a relativistic approach and results for muonic

X-ray fluorescence spectrum of highly charged Fe ions driven by strong free-electron-laser fields

^{205}\mathrm{Bi}, ^{147}\mathrm{Sm}

Finite nuclear size effect to the fine structure of heavy muonic atoms

, and

Hyperfine splitting in simple ions for the search of the variation of fundamental constants

^{89}\mathrm{Zr}

Identifications of [equation presented] and [equation presented] EUV transitions of promethium-like Pt, Ir, Os and Re

are presented. The hyperfine structure due to magnetic dipole and electric quadrupole splitting is calculated in first-order perturbation theory, using extended nuclear charge and current distributions. The leading correction from quantum electrodynamics, namely vacuum polarization in Uehling approximation, is included as a potential directly in the Dirac equation. Also, an effective screening potential due to the surrounding electrons is calculated, and the leading relativistic recoil correction is estimated.