Isoelectronic trends of the E1-forbidden decay rates of Al-, Si-, P-, and S-like ions of Cl, Ti, Mn, Cu, and Ge

Abstract

Working towards a reliable grid of atomic lifetime data on 3s23pk ground configuration levels of Al-, Si-, P-, and S-like ions of iron group elements, measurements on electric-dipole forbidden decays in ions of Cl, Ti, Mn, Cu, and Ge have been done at a heavy-ion storage ring that complement earlier measurements on Fe, Co, Ni, and Cu ions. The data are compared isoelectronically with various predictions, especially those made by the multi-reference Møller–Plesset technique, and with the few results available from other experimental approaches. Apparent perturbations of otherwise smooth isoelectronic trends of some of the data are identified with the occurrence of specific cascades from long-lived 3d levels.

Electron-correlation effects on the3Cto3Dline-intensity ratio in the Ne-like ionsAr8+Santana1, Lepson2, Beiersdörfer3 2015Phys. Rev. ASelf Cite305210View full textAdd to dashboardCite

“…This experiment-theory interchange helped to develop methods to optimize the calculation of excitation energies. For radiative rates, on the order hand, there are fewer experimental results and the benchmarking of theoretical methods has been performed with ions other than neonlike [87][88][89][90][91]; a very few cases where neonlike high-Z ions were studied [92,93] are the exception. (There also have been studies of transition rates in low-Z ions of the Ne isoelectronic sequence, with reviews that illustrate the pitfalls of experiment and calculation [94][95][96]).…”

A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions

“…The lowest-Z measurements on ions of the P I isoelectronic sequence have been reported for Z = 25 (Mn), and the highest-Z ones for Z = 36 (Kr). Figure 6 shows comparisons of these lifetime data [15][16][17][18][19] obtained by work with a variety of ion traps (electrostatic (Kingdon) trap, heavy-ion storage ring, electron beam ion trap) with various predictions. To accommodate all experimental and computational results on a common footing and practical scale, they are displayed by their (relative) difference from a computed reference set.…”

“…To accommodate all experimental and computational results on a common footing and practical scale, they are displayed by their (relative) difference from a computed reference set. Since not all computations using a given approach [21,[27][28][29][30] had been applied to all elements in this range, computations employing a multi-reference Møller-Plesset code were executed by Diaz, Ishikawa, and Santana at the University of Puerto Rico (UPR) [18] to provide such a reference. Strikingly, for high values of the nuclear charge in this sample, Z ≈ 36, all computational predictions agree with each other to within about 10%, whereas at the low-Z end of the display, near Z = 22, the bandwidth of the predictions spans about 30%.…”

“…Other computational results: Mendoza & Zeippen [26], Huang [27], Biémont & Hansen [28], Kaufman & Sugar [29], NIST [21]. [15,16], the heavy-ion storage ring TSR [17,18], and an electron beam ion trap (EBIT) [19]. The reference computations were executed at the University of Puerto Rico (UPR) [18].…”

“…In planetary nebulae the density is much lower, for example n e = 10 4 cm −3 (see [11] and references therein), at temperatures of 10 4 K (1 eV) and lower. For the diagnostic studies of the solar corona, the levels of primary interest in suitable highly charged ions (say, Fe 8+ to Fe 18+ ) feature lifetimes in the range of several milliseconds up to seconds and have been investigated in several types of ion traps (see [15][16][17][18][19][20] and discussion below). For the investigation of density effects in planetary nebulae, ions with level lifetimes longer by yet another 3 to 4 orders of magnitude are required.…”