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[en] Mass spectra of van der Waals or hydrogen-bonded clusters feature characteristic lower size limits for the observability of multiply charged ions. The author reviews present knowledge about the origin of this effect, including recent progress in determining decay channels of metastable, multiply charged clusters. 53 refs.; 5 figs
[en] The U-400 Ion Cyclotron currently under construction at the JINR Laboratory of Nuclear Reactions is a development of the technique of acceleration of multiply-charged ions used in this Laboratory with the U-200 and U-300 previous cyclotrons
[en] Possibilities of the new quasirelativistic approach designed for ab initio calculations of spectral characteristics of highly charged ions and heavy atoms are briefly described and illustrated with an example of a study of spectral characteristics of gallium-like Molybdenum and Tungsten.
[en] The double and triple photoionization of ground-state lithium is investigated in the high-energy limit. Relative to the total photoionization cross section, the fraction of two-electron escape processes is 0.0325, while the fraction leading to triple escape is only 5.6x10-6 . Double ionization via Li+ autoionizing states accounts for more than 40% of the two-electron escape processes. A comparison of the high-energy-limit calculations with experiments at 424eV shows close agreement for double photoionization. A factor of 10 discrepancy exists for triple photoionization at 424eV, however, which presumably indicates that the high-energy limit has not yet been reached. copyright 1998 The American Physical Society
[en] A number of recent atomic lifetime measurements on multiply charged ions have reported uncertainties lower than 1%. Such a level of accuracy challenges theory, which is a good thing. However, a few lessons learned from earlier precision lifetime measurements on atoms and singly charged ions suggest to remain cautious about the systematic errors of experimental techniques.
[en] How long does an atom 'live' in an excited state, when due to conservation rules and symmetry principles the 'normal' electric dipole decay to the ground state is forbidden? Then spin-changing 'intercombination' transitions and electric dipole 'forbidden' decays occur that are important for the diagnostics of low-density solar corona] and terrestrial plasmas. Regular 'allowed' and intercombination transitions in highly charged ions (picosecond and nanosecond lifetime range) have previously been measured with straight, foil-excited, fast ion beams. For ions with only one or two electrons in the valence shell, very long sections of the isoelectronic sequence have been covered this way, yielding experimental tests of theoretical predictions of transition rates that are good to a few percent. Recently the situation has become much better than this for lifetimes in the millisecond range. Here the technique of optical observation at a heavy-ion storage ring permits atomic lifetime measurements on intercombination and forbidden transitions with a precision that often is better than 1 %, which is clearly surpassing the precision range of typical conventional ion trap data. The electron beam ion trap (EBIT) exhibits a similar precision in the 'X-ray' range, and it has reached uncertainties of a few percent in some measurements of optical transitions