Hyperfine-structure-resolved laser spectroscopy of many-electron highly charged ions

Abstract

Hyperfine structures of highly charged ions (HCIs) are favourable spectroscopic targets for exploring fundamental physics along with nuclear properties. Recent proposals of HCI atomic clocks highlight their importance, especially for many-electron HCIs, and they have been theoretically investigated by refining atomic-structure calculations. However, developments in hyperfine spectroscopy of many-electron HCIs have not proceeded due to experimental difficulty. Here, we demonstrate hyperfine-structure-resolved laser spectroscopy of HCIs in an electron beam ion trap plasma, employing the magnetic-dipole transition in the 4d95s state of 127I7+. Ion-state manipulation by controlled electron collisions in the well-defined laboratory plasma enables laser-induced fluorescence spectroscopy of trapped HCIs. The observed spectrum of evaporatively cooled ions under low magnetic fields shows characteristic features reflecting the hyperfine structures. The present demonstration using combined optical and plasma approaches provides a benchmark for state-of-the-art atomic calculations of hyperfine structures in many-electron HCIs, and offers possibilities for a variety of unexploited experiments.

Experimental and theoretical Ritz–Rydberg analysis of the electronic structure of highly charged ions of lead and bismuth by optical spectroscopy

“…Our study complements recent works from other groups that have investigated various interesting ionic species, for instance [22][23][24][25][26][27][28][29][30], using electron beam ion traps (EBITs). These works also emphasized heavy ions, orbital crossings, and hyperfine structure studies (e.g.…”

“…These works also emphasized heavy ions, orbital crossings, and hyperfine structure studies (e.g. [29] on I VIII). It is interesting to mention here that such hyperfine anomalies in neutrals (see [31] for a recent example, and [32] for a general review) can be tools for searching for New Physics, and that the same applies to HCI as well.…”

Injection of metallic elements into an electron-beam ion trap using an electron impact metal vapor source

“…This previous theoretical study suggested that this transition possesses relatively large hyperfine splitting. We consider that this transition is a practical target for the hyperfine spectroscopy under the quasi-Zeeman-free EBIT field, which we have recently demonstrated [17].…”

“…For instance, the injection methods using an ion source require a sophisticated ion-beam control with specialized ion-beam optics to allow injection along the EBIT axis. MEVVA and laser ablation are time-dependent injection methods, and thus need careful consideration to apply them to time-dependent experiments such as resonant process observations by sweeping the electronbeam energy [16], time-resolved laser spectroscopy [17], and lifetime measurements [18]. While a Knudsen cell connected to an EBIT is versatile for the continuous injection of metals, the melting point of the crucible generally restricts the maximum operating temperature, making vapor generation difficult for metals with extremely low vapor pressure, such as W, Ta, Re, and Nb.…”

Relativistic atomic structure calculations of Li-like ions used for plasma diagnostic studies

“…self-energy and vacuum polarization are plays a dominant role in highly charged ions properties. Currently, the active fundamental research areas such as precise measurement of fine structure constant needs accurate atomic clocks based on highly charged ion and these individual QED corrections plays a crucial role in their development [73][74][75].…”