Resonance strengths for KLL dielectronic recombination of highly charged mercury ions and improved empirical Z -scaling law

Abstract

Theoretical and experimental resonance strengths for KLL dielectronic recombination (DR) into He-, Li-, Be-, and B-like mercury ions are presented, based on state-resolved DR x-ray spectra recorded at the Heidelberg electron beam ion trap. The DR resonance strengths were experimentally extracted by normalizing them to simultaneously recorded radiative recombination signals. The results are compared to state-of-the-art atomic calculations that include relativistic electron correlation and configuration mixing effects. Combining the present data with other existing ones, we derive an improved semi-empirical Z-scaling law for DR resonance strength as a function of the atomic number, taking into account higher-order relativistic corrections, which are especially relevant for heavy highly charged ions. arXiv:1807.03366v2 [physics.atom-ph]

Higher-Order Recombination Processes in Argon Ions Observed via X-ray Emission in an EBIT

“…Moreover, this way of presenting data enabled the identification of the charge state of the active ion. These data together with other measured ions will be used in a future publication to verify the DR Z-scaling laws ( [11] and references therein). Moreover, in Figure 5, different processes were shown with different symbols: DR (square), TR (circle), and QR (triangle).…”

Atomic structure and collision dynamics with highly charged ions

“…In addition to DR experiments at storage rings, DR spectroscopy has also been carried out at EBITs to investigate HCI structures around the world. Since the first experiment [53] at the Livermore electron beam ion trap (EBIT), many measurements have been conducted for Helike ions, such as argon, [54] titanium, [55] iron, [56] nickel, [53] germanium, [57] krypton, [58] molybdenum, [59] iodine, [60] xenon, [61] barium, [59] tungsten, [62] mercury, [63] and isoelectronic sequences with lower charge state. [61,64] Up to now, only a few measurements for H-like ions, such as argon, [65] titanium, [66] and krypton, [67] have been studied due to the experimental difficulties at EBITs.…”

“…The method has been well applied to measure the DR resonance strength that involves an inner-shell electron excitation. [61][62][63][64] Many other measurements use a steady-state running mode. [60,92] In this mode, the electron beam energy is slowly scanned to ensure that the charge state distribution (CSD) reaches equilibrium at each beam energy.…”