Discrepancies in Atomic Data and Suggestions for their Resolutions

The analysis and modelling of a range of plasmas (for example: astrophysical, laser-produced and fusion), require atomic data for a number of parameters, such as energy levels, radiative rates and electron impact excitation rates, or equivalently the effective collision strengths. Such data are desired for a wide range of elements and their many ions, although all elements are not useful for all types of plasmas. Since measurements of atomic data are mostly confined to only a few energy levels of some ions, calculations for all parameters are highly important. However, often there are large discrepancies among different calculations for almost all parameters, which makes it difficult to apply the data with confidence. Many such discrepancies (and the possible remedies) were discussed earlier (Fusion Sci. Tech. 2013, 63, 363). Since then a lot more anomalies for almost all of these atomic parameters have come to notice. Therefore, this paper is a revisit of various atomic parameters to highlight the large discrepancies, their possible sources and some suggestions to avoid those, so that comparatively more accurate and reliable atomic data may be available in the future.Comment: 18 pages of text including 7 figures will appear in Atoms 5 (2017

Energy Levels and Radiative Rates for Transitions in F-like Sc~XIII and Ne-like Sc~XII and Y~XXX

Energy levels, radiative rates and lifetimes are reported for F-like Sc~XIII and Ne-like Sc~XII and Y~XXX for which the general-purpose relativistic atomic structure package ({\sc grasp}) has been adopted. For all three ions limited data exist in the literature but comparisons have been made wherever possible to assess the accuracy of the calculations. In the present work the lowest 102, 125 and 139 levels have been considered for the respective ions. Additionally, calculations have also been performed with the flexible atomic code ({\sc fac}) to (particularly) confirm the accuracy of energy levels.Comment: 24pp of Text including 12 Tables will appear in Atoms 6 (2018

Electron impact excitation of F-like W LXVI

Electron impact excitation collision strengths are calculated for all transitions among 113 levels of the 2s$^2$2p$^5$, 2s2p$^6$, 2s$^2$2p$^4$3$\ell$, 2s2p$^5$3$\ell$, and 2p$^6$3$\ell$ configurations of F-like W~LXVI. For this purpose Dirac Atomic R-matrix Code (DARC) has been adopted and results are listed over a wide energy range of 1000 to 6000 Ryd. For comparison purpose analogous calculations have also been performed with the Flexible Atomic Code (FAC), and the results obtained are comparable with those from DARC.Comment: 17p paper including 2 Tables and 4 Figures will appear in vol. 4 of ATOMS in 201

A Simpler Route for Making Nitrogen-Alkene Rings

A common nitrogen building block used in many natural product and drug syntheses can now be made in its unprotected form in a single step.</jats:p