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Extreme ultraviolet spectra of Na-like and Mg-like Os and Ir were recorded at the National Institute of Standards and Technology using a grazing incidence spectrometer. We report a method in EBIT spectral analysis that reduces signals from contaminant lines of known or unknown origin. We utilize similar ion charge distributions of heavy highly charged ions that create similar potentials for lighter contaminating background elements. First-order approximations to ion distributions are presented to demonstrate differences between impurity elements with and without heavy ions present. [ABSTRACT FROM AUTHOR]

Precise spectroscopic experiments with light atoms can provide information about nuclear properties that are very difficult to obtain in electron scattering experiments. For example, relative nuclear radii of low-Z isotopes can be determined accurately from isotope shifts. Theory has attained sufficient accuracy to study exotic, short-lived halo nuclei by interpreting precise spectroscopic measurements. However, serious inconsistencies remain in the measured isotope shifts for the D1 and D2 lines of the stable isotopes ([sup.6]Li and [sup.7]Li). The latest experiments, within the last decade, are in strong disagreement with each other and with theory. We report on the progress of a new experiment at the National Institute of Standards and Technology (NIST) to measure these lithium D lines using an optical frequency comb. A preliminary result for the splitting isotope shift (SIS) is presented. PACS Nos: 31.30.Gs, 32.10.Fn, 42.62.Eh Des mesures spectroscopiques precises sur des atomes legers peuvent nous fournir de l'information sur des proprietes nucleaires qui sont tres difficiles a obtenir a partir de la diffusion d'electrons. Par exemple, il est possible de determiner precisement les rayons relatifs d'isotopes de faible Z a partir du deplacement isotopique. La theorie est maintenant suffisamment precise pour etudier des noyaux exotiques, des noyaux a halo de courte vie, en interpretant des mesures spectroscopiques precises. Cependant, certaines incoherences continuent d'exister dans les deplacements isotopiques mesures pour les lignes D1 et D2 des isotopes stables [sup.6]Li et [sup.7]Li. Les experiences de la derniere decennie sont en fort desaccord les unes avec les autres et avec la theorie. Nous faisons ici rapport sur les progres faits dans une nouvelle experience au National Institute of Standards (NIST) pour mesurer ces lignes D du lithium en utilisant un peigne de frequences optiques. Nous presentons les resultats preliminaires du deplacement isotopique de division de ligne (SIS). [Traduit par la Redaction], 1. Introduction Advances in the spectroscopy and theory of few-electron atoms over the last two decades have enabled precision spectroscopic experiments to probe and measure nuclear properties that are otherwise [...]

2014 marks the 100th anniversary of the birth of Martin Gardner, a man whose writings helped inspire generations of young students to pursue a career in physics and mathematics. From his first to his last, and many in between, Gardner's publications often combined magic and science. A recurring theme was the clever use of physical principles to produce an apparently miraculous effect that stimulated the mind to wonder "how is that possible?" In contrast to the disconnect between science and mystery that one often encounters in teaching today, Gardner embraced these two disparate elements, and fused them into a whole that made learning a joy.

Extreme ultraviolet spectra of the L-shell ions of highly charged yttrium (Y26+-Y26+) were observed in the electron beam ion trap of the National Institute of Standards and Technology using a flat-field grazing-incidence spectrometer in the wavelength range of 4 nm-20 nm. The electron beam energy was systematically varied from 2.3 keV-6.0 keV to selectively produce different ionization stages. Fifty-nine spectral lines corresponding to Dn = 0 transitions within the n = 2 and n = 3 shells have been identified using detailed collisional-radiative (CR) modeling of the non-Maxwellian plasma. The uncertainties of the wavelength determinations ranged between 0.0004 nm and 0.0020 nm. Li-like resonance lines, 2s-2p1/2 and 2s-2p3/2, and the Na-like D lines, 3s-3p1/2 and 3s-3p3/2, have been measured and compared with previous measurements and calculations. Forbidden magnetic dipole (M1) transitions were identified and analyzed for their potential applicability in plasma diagnostics using large-scale CR calculations including approximately 1.5 million transitions. Several line ratios were found to show strong dependence on electron density and, hence, may be implemented in the diagnostics of hot plasmas, in particular in fusion devices. [ABSTRACT FROM AUTHOR]