Using fast-ion-beam laser-fluorescence spectroscopy (FIBLAS), we have measured the hyperfine structure (hfs) of 14 levels and an additional four transitions in Dy II and the isotope shifts (IS) of 12 transitions in the wavelength range of 422–460 nm. These are the first precision measurements of this kind in Dy II. Along with hfs and IS, new undocumented transitions were discovered within 3 GHz of the targeted transitions. These atomic data are essential for astrophysical studies of chemical abundances, allowing correction for saturation and the effects of blended lines. Lanthanide abundances are important in diffusion modeling of stellar interiors, and in the mechanisms and history of nucleosynthesis in the universe. Hfs and IS also play an important role in the classification of energy levels, and provide a benchmark for theoretical atomic structure calculations.

The 3d34p, 3d35p and 3d24s4p odd configurations of the V II spectrum have been reanalysed and three 3d24s4p triplets are assigned higher energies than previously proposed. We have determined the fine structure parameters, the largest and next largest eigenvector percentages of levels, their calculated Landé gJ-factors and predicted positions for missing experimental levels up to 100,000 cm-1 for the 3d24s4p configuration. Furthermore for the first time a hyperfine structure (HFS) parametric treatment, involving levels of these two configurations has been carried out. The deduced single-electron HFS parameter values are successfully checked with those obtained by means of ab initio calculations.

Collinear fast-ion-beam laser spectroscopy is a very high resolution probe for measuring ion-beam energy distributions and atomic structure parameters of interest in nuclear physics, atomic physics, and astrophysics. We have used offline 10-keV beams of atomic ions and a CW laser system to study the behavior of a Penning ion source and to measure hyperfine structure, isotope shifts, atomic lifetimes, spontaneous-emission branching fractions, oscillator strengths, and absolute wavelengths of a variety of atomic species from the lanthanide and transition-metal groups.

Kurzfassung Im Rahmen des Niedersächsischen Innovationsverbunds Plasmatechnik (NIP) werden neue Anwendungen der Plasmatechnologie in den Bereichen Fertigungstechnik und Materialanalyse bis hin zur Medizintechnik erschlossen sowie ihr ökonomischer und ökologischer Nutzen evaluiert. Im Bereich der Materialanalyse zählt dazu die Entwicklung eines spektroskopischen Verfahrens unter Nutzung eines ökoeffizienten Atmosphärendruckplasmas zur Emissionsanregung. Zum Einsatz kommt hierbei eine im Rahmen des Projekts entwickelte neuartige Plasmaquelle, die für die Analyse gasförmiger, flüssiger und fester Proben in unterschiedlichen Modi betrieben werden kann. Der Energieeintrag in das Probenmaterial durch diese Plasmaquelle beträgt hierbei wenige Mikrojoule. An verschiedenen Probenmaterialien wurde gezeigt, dass sich dieses Verfahren zur Erzeugung und Detektion elementspezifischer Spektrallinien eignet.

We have applied fast-ion-beam laser-fluorescence spectroscopy to measure the magnetic dipole hyperfine structure (hfs) constants of 24 even levels and 31 odd levels in 51V II. These are the first published data for hfs in this ion. These results will be very useful for the measurement of stellar photospheric abundances, studies of the history of nucleosynthesis and the testing of models of stellar interiors. The rather large hyperfine splittings in 51V II significantly affect the saturation and width of absorption lines, and this must be taken into account in order to derive accurate abundances and stellar rotation and micro- and macro-turbulence parameters, as well as to help determine if line blending is occurring.

We have developed a version of the Frankfurt Penning ion source that produces ion beams with very low energy spreads of ∼3eV, while operating in a new discharge mode characterized by very high pressure, low voltage, and high current. The extracted ions also comprise substantial metastable and doubly charged species. Detailed studies of the operating parameters of the source showed that careful adjustment of the magnetic field and gas pressure is critical to achieving optimum performance. We used a laser-fluorescence method of energy analysis to characterize the properties of the extracted ion beam with a resolving power of 1×104, and to measure the absolute ion beam energy to an accuracy of 4eV in order to provide some insight into the distribution of plasma potential within the ion source. This characterization method is widely applicable to accelerator beams, though not universal. The low energy spread, coupled with the ability to produce intense ion beams from almost any gas or conducting solid, make this source very useful for high-resolution spectroscopic measurements on fast-ion beams.

We have applied fast-ion-beam laser-fluorescence spectroscopy to measure the isotope shifts of 73 optical transitions in the wavelength range 421.5–455.8nm and the hyperfine structures of 35 even parity and 33 odd parity levels in Gd II. Many of the isotope shifts and hyperfine structure measurements are the first for these transitions and levels. These atomic data can be used to correct for saturation and blending in the analysis of stellar spectra to determine chemical abundances. As a result, they have an important impact on studies of the history of nucleosynthesis in the Universe and on the use of photospheric abundance anomalies in Chemically Peculiar stars to infer indirect information about stellar interiors.

Atomic oscillator-strength data are of great interest to astronomers studying photospheric chemical abundances, stellar interiors and nucleosynthesis. We review the classic methods of measurement and then discuss our approach, which is based on fast-ion-beam laser-fluorescence techniques for both lifetime and branching-fraction measurements. Recently obtained large data sets in singly ionized lanthanides are discussed, with several examples illustrating the major advantages of this method: unambiguous identification of the upper level of a transition and greatly reduced spectral line blending.

Using x-ray diffraction and beam-foil spectroscopy, we have determined precise wavelengths for Lyman ${\ensuremath{\alpha}}_{1}$ and Lyman ${\ensuremath{\alpha}}_{2}$ in hydrogenic germanium of $1.166\phantom{\rule{0.2em}{0ex}}993\phantom{\rule{0.2em}{0ex}}8\ifmmode\pm\else\textpm\fi{}33\ifmmode\pm\else\textpm\fi{}169$ and $1.172\phantom{\rule{0.2em}{0ex}}433\phantom{\rule{0.2em}{0ex}}6\ifmmode\pm\else\textpm\fi{}39\ifmmode\pm\else\textpm\fi{}170\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. Hydrogenic germanium ${\mathrm{Ge}}^{31+}$ $1s\text{\ensuremath{-}}2{p}_{3∕2}$ and $1s\text{\ensuremath{-}}2{p}_{1∕2}$ Lamb shifts are measured to be $66\phantom{\rule{0.2em}{0ex}}080\ifmmode\pm\else\textpm\fi{}237\ifmmode\pm\else\textpm\fi{}1121$ and $67\phantom{\rule{0.2em}{0ex}}169\ifmmode\pm\else\textpm\fi{}281\ifmmode\pm\else\textpm\fi{}1237\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, respectively. This $14\phantom{\rule{0.3em}{0ex}}\mathrm{ppm}$ measurement of the wavelengths thus provides a 1.8% measurement of the $2p\text{\ensuremath{-}}1s$ Lamb shift and is an improvement by a factor of 3 over previous work. Fitting the full two-dimensional dispersion relation, including Balmer and Lyman series, limits random and systematic correlation of parameters. Dominant systematics are due to diffraction parameters including crystal thickness and alignment, differential Doppler shifts due to the variable location of spectral emission downstream of the beam-foil target, and dielectronic, $2s\text{\ensuremath{-}}1s$, and $4f\text{\ensuremath{-}}2p$ satellites. Models developed are applicable to all relativistic plasma modeling in beam-foil spectroscopy at accelerators. The technique also reports the germanium $2{p}_{3∕2}\text{\ensuremath{-}}2{p}_{1∕2}$ fine structure as $397\phantom{\rule{0.2em}{0ex}}617\ifmmode\pm\else\textpm\fi{}251\ifmmode\pm\else\textpm\fi{}512\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, representing a 0.14% measurement of the fine structure and a 71% measurement of the QED contribution to the hydrogenic germanium fine structure, an improvement of a factor of 6 over previous work. We also report a precise measurement of heliumlike resonances and fine structure.

The spontaneous-emission branching fractions of 32 levels of Pr II were measured by the fast-ion-beam laser-induced-fluorescence technique. The levels studied had energies from similar to 21 500 to similar to 29 000 cm(-1), and the decay branches detected were in the range from 250 to 850 nm. The experimental uncertainties are within 10%. Using our previously measured radiative lifetimes, we determined the Einstein A coefficients and oscillator strengths for 260 transitions. The results are important for stellar elemental abundance determinations.

We measured the spontaneous-emission branching ratios of 69 levels in Sm II selectively populated via single-frequency laser excitation of a 10 keV ion beam. The levels studied had term energies up to 29 600 cm–1, and decay branches with spontaneous emission in the range 250–850 nm were detected. The experimental accuracy was in the range of 10%. We used these branching ratios along with our previously determined radiative lifetimes to infer transition probabilities and oscillator strengths for 608 transitions in the wavelength range 363–771 nm, which are useful for stellar abundance determinations.PACS Nos.: 32.70.Cs, 95.30.Ky

The high-resolution spectra of 110 transitions in Nd II over the range 418–465 nm were observed using the collinear fast-ion-beam/laser method (FIBLAS). The lower states of these transitions include the ground state and 10 metastable even-parity states with energies up to 5986 cm –1 . The 64 odd-parity upper states have energies up to 29 434 cm –1 . For each transition isotope shifts were measured for all the stable isotopes (mass numbers 142, 143, 144, 145, 146, 148, and 150), as well as hyperfine parameters for the two odd-mass-number isotopes. These quantities are important in modeling profiles of absorption lines in stellar atmospheres to obtain abundances, and in the classification of atomic energy levels. PACS Nos.: 31.30.Gs, 32.10.Fn, 95.30.Ky

We have measured the absolute wave numbers of 39 transitions of ^130Te_2 spanning the spectral region of 420.9-464.6 nm to an accuracy of better than 2 parts in 10^9 by use of saturation spectroscopy and Fabry-Pérot interferometry. These measurements provide a set of convenient and accurate transfer standards for laser wavelength calibration spanning the entire Stilbene-420 dye-tuning curve.

We have measured the absolute wave numbers of 39 transitions of Te-130(2) spanning the spectral region of 420.9-464.6 nm to an accuracy of better than 2 parts in 109 by use of saturation spectroscopy and Fabry-Perot interferometry. These measurements provide a set of convenient and accurate transfer standards for laser wavelength calibration spanning the entire Stilbene-420 dye-tuning curve. (c) 2005 Optical Society of America.

We have constructed a broadband apparatus for wavelength metrology capable of absolute accuracy at a level of better than 2 parts in 109. An evacuated plane-parallel Fabry–Pérot interferometer with continuously adjustable mirror separation is used to compare the wavelength of a single-frequency tunable laser with that of an iodine-stabilized HeNe laser used as a wavelength standard. This work details apparatus construction, a thorough investigation of systematic errors, and data analysis. The wavelengths of five Doppler-free Te2130 transitions in the region from 475.6 to 490.8 nm have been measured and are found to be in excellent agreement with previous measurements. In addition, the wavelengths of five previously unmeasured Te2130 transitions spanning the region from 424.9 to 462.3 nm have been determined for use as new reference wavelength standards.

We have measured the isotope shifts of 87 transitions in Sm II in the 418-465 nm spectral region and the magnetic-dipole and electric-quadrupole hyperfine constants of 13 low-lying even-parity metastable levels and 76 odd-parity levels. These results will be immediately applicable to stellar spectroscopy.

We have measured the isotope shifts of 87 transitions in Sm II in the 418–465 nm spectral region and the magnetic-dipole and electric-quadrupole hyperfine constants of 13 low-lying even-parity metastable levels and 76 odd-parity levels. These results will be immediately applicable to stellar spectroscopy.PACS Nos.: 32.30.–r, 32.10.–f