Observation of Visible and uv Magnetic Dipole Transitions in Highly Charged Xenon and Barium

Abstract

We have observed an unusual transition which is predicted to result in visible and near-uv emission from very highly charged titaniumlike ions spanning the entire upper half of the periodic table. Measurements of the wavelengths of the 3d 'D2-D3 transitions in Ba+ and Xe+ are in surprisingly poor agreement with ab initio calculations. This work was carried out in an electron beam ion trap and demonstrates that such a device can be an important tool for visible spectroscopy of highly charged ions. PACS numbers: 32.70.n, 31.25.v, 52.25.b, 52.70.KzAlthough ions having identical numbers of electrons display similar spectral structure, the scale of many atomic properties changes dramatically as the nuclear charge (Z) is increased along an isoelectronic sequence. One example is the rapid decrease in transition wavelengths leading to the characteristic emission of light in the x-ray region of the spectrum for very highly charged ions. It was therefore unusual when Feldman, Indelicato, and Sugar [1] reported calculations predicting a small set of observable visible and near-uv magnetic dipole (Ml) lines for highly charged ions in the titaniumlike isoelectronic sequence. The upper levels of these transitions lie within the ground term, and, therefore, in low density plasmas (~10'3 cm '), where competition from electron

Direct Observation of the Spontaneous Emission of the Hyperfine TransitionF=4toF=3in Ground State HydrogenlikeLópez‐Urrutia1, Beiersdörfer2, Savin3 et al. 1996Phys. Rev. Lett.17211083View full textAdd to dashboardCite

“…The SuperEBIT has been used to perform very accurate spectroscopic measurements of highly charged ions in the x-ray regime [6], while no such measurements have been made in the optical. The possibility of performing spectroscopy of highly charged ions in the visible on a low-energy EBIT was demonstrated only recently by Morgan et al [7], who measured optical transitions in V-like and Ti-like Xe and Ba ions in the NIST EBIT.…”

Trapped highly charged ion plasmas

“…There are a few unusual transitions, however, that stay in the visible range, because of a fortuitous energy-level crossing. One of these transitions has been predicted [59] and found [18] in the Ti-like isoelectronic sequence. There are also transitions that during their rapid scaling to shorter wavelengths from the infrared or microwave range, pass through the visible range at a particular charge state or narrow range of charge states.…”

“…Some earlier unpublished work using CCD imaging was briefly described in a Livermore annual report [58]. The lack of any work in imaging the ion cloud immediately after the first EBIT came online can be partly understood by realizing that it was quite a few years before the first visible-light spectroscopy was done on an EBIT [18]. The reason for this is that the scaling laws cause most of the transition energies to shift into the x-ray energy range as the ion charge is increased.…”

“…Shortly after this, the National Institute of Standards and Technology (NIST) became the second place in the world to have a working EBIT [6,7], followed by new constructions in several other laboratories [8-121. EBITs are not the only machines that can create ions in high charge states, but certainly they are one of the most versatile, offering great control over the experimental conditions in which highly charged ions are produced. The success of the EBIT is proven by the numerous widely-cited experiments that have been carried out by since its inception [4,5,[13][14][15][16][17][18].…”

Progress in Impurity-Related Physics Experiments in LHD

“…12 Typical error bars for the LHD [41], tokamak [37], and EBIT [45][46][47] in measured wavelengths of the M1 transitions of (a) Si-like KrXXIII, (b) S-like MoXXIX, and (c) Ti-like XeXXXIII.…”