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Title: Extreme-ultraviolet spectroscopy of highly charged xenon ions created using an electron-beam ion trap

Abstract

Extreme-ultraviolet spectra of xenon ions have been recorded in the 4.5 to 20 nm wavelength region using an electron beam ion trap and a flat field spectrometer. The electron beam energy was varied from 180 eV to 8 keV and radiation from charge states Xe{sup 6+} to Xe{sup 43+} was observed. Our measured wavelengths were compared to atomic structure calculations using the Cowan suite of codes. We have measured seventeen previously unreported features corresponding to transitions in Xe{sup 35+} through to Xe{sup 41+} with estimated wavelength uncertainties of {+-}0.003 nm. It was found that for the case of continuous injection of neutral xenon gas a wide range of charge states were always present in the trap but this charge state distribution was greatly narrowed, towards higher charge states, if a sufficiently low gas injection pressure was employed. The energy dependence of spectral lines arising from Xe{sup 42+} and Xe{sup 43+} revealed enhancement of the total ionization cross sections, due to excitation-autoionization of n=2 electrons to n=3 levels, in the Xe{sup 41+} and Xe{sup 42+} charge states.

Authors:
; ;  [1]; ; ; ;  [2]
  1. School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
  2. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
Publication Date:
OSTI Identifier:
20982317
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.75.032520; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; AUTOIONIZATION; CATIONS; CHARGE STATES; CROSS SECTIONS; ELECTRON BEAMS; ELECTRONS; ENERGY DEPENDENCE; EV RANGE 100-1000; EXCITATION; EXTREME ULTRAVIOLET SPECTRA; GAS INJECTION; INJECTION; KEV RANGE 01-10; MULTICHARGED IONS; SPECTROSCOPY; TRAPS; WAVELENGTHS; XENON; XENON IONS

Citation Formats

Fahy, K., Sokell, E., O'Sullivan, G., Aguilar, A., Pomeroy, J. M., Tan, J. N., and Gillaspy, J. D. Extreme-ultraviolet spectroscopy of highly charged xenon ions created using an electron-beam ion trap. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.032520.
Fahy, K., Sokell, E., O'Sullivan, G., Aguilar, A., Pomeroy, J. M., Tan, J. N., & Gillaspy, J. D. Extreme-ultraviolet spectroscopy of highly charged xenon ions created using an electron-beam ion trap. United States. doi:10.1103/PHYSREVA.75.032520.
Fahy, K., Sokell, E., O'Sullivan, G., Aguilar, A., Pomeroy, J. M., Tan, J. N., and Gillaspy, J. D. Thu . "Extreme-ultraviolet spectroscopy of highly charged xenon ions created using an electron-beam ion trap". United States. doi:10.1103/PHYSREVA.75.032520.
@article{osti_20982317,
title = {Extreme-ultraviolet spectroscopy of highly charged xenon ions created using an electron-beam ion trap},
author = {Fahy, K. and Sokell, E. and O'Sullivan, G. and Aguilar, A. and Pomeroy, J. M. and Tan, J. N. and Gillaspy, J. D.},
abstractNote = {Extreme-ultraviolet spectra of xenon ions have been recorded in the 4.5 to 20 nm wavelength region using an electron beam ion trap and a flat field spectrometer. The electron beam energy was varied from 180 eV to 8 keV and radiation from charge states Xe{sup 6+} to Xe{sup 43+} was observed. Our measured wavelengths were compared to atomic structure calculations using the Cowan suite of codes. We have measured seventeen previously unreported features corresponding to transitions in Xe{sup 35+} through to Xe{sup 41+} with estimated wavelength uncertainties of {+-}0.003 nm. It was found that for the case of continuous injection of neutral xenon gas a wide range of charge states were always present in the trap but this charge state distribution was greatly narrowed, towards higher charge states, if a sufficiently low gas injection pressure was employed. The energy dependence of spectral lines arising from Xe{sup 42+} and Xe{sup 43+} revealed enhancement of the total ionization cross sections, due to excitation-autoionization of n=2 electrons to n=3 levels, in the Xe{sup 41+} and Xe{sup 42+} charge states.},
doi = {10.1103/PHYSREVA.75.032520},
journal = {Physical Review. A},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • We have investigated extreme ultraviolet emission from highly charged barium using a compact electron beam ion trap at the Tokyo EBIT laboratory. The spectra were recorded for several beam energies ranging from 440 to 740 eV, while keeping the electron beam current constant at 10 mA. Radiation from charge states Zr-like Ba{sup 16+} to As-like Ba{sup 23+} were recorded and identified by varying the electron beam energy across the ionization thresholds and comparing with calculated results. The calculations were performed with a detailed relativistic configuration interaction approach using the Flexible Atomic Code. Several new lines belonging to electric dipole transitions were observedmore » and identified.« less
  • Spectra in the extreme ultraviolet range from 107 to 353 A emitted from Fe ions in various ionization stages have been observed at the Heidelberg electron beam ion trap (EBIT) with a flat-field grating spectrometer. A series of transition lines and their intensities have been analyzed and compared with collisional-radiative simulations. The present collisional-radiative model reproduces well the relative line intensities and facilitates line identification of ions produced in the EBIT. The polarization effect on the line intensities resulting from nonthermal unidirectional electron impact was explored and found to be significant (up to 24%) for a few transition lines. Basedmore » upon the observed line intensities, relative charge state distributions (CSD) of ions were determined, which peaked at Fe{sup 23+} tailing toward lower charge states. Another simulation on ion charge distributions including the ionization and electron capture processes generated CSDs which are in general agreement with the measurements. By observing intensity ratios of specific lines from levels collisionally populated directly from the ground state and those starting from the metastable levels of Fe XXI, Fe X and other ionic states, the effective electron densities were extracted and found to depend on the ionic charge. Furthermore, it was found that the overlap of the ion cloud with the electron beam estimated from the effective electron densities strongly depends on the charge state of the ion considered, i.e. under the same EBIT conditions, higher charge ions show less expansion in the radial direction.« less
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  • The results of experimental study of magnetic dipole (M1) transitions in highly charged ions of argon (Ar9+, Ar10+, Ar13+ and Ar14+) and krypton (Kr18+ and Kr22+) are presented. The forbidden transitions of the highly charged ions in the visible and near UV range of the photon emission spectra have been measured with accuracy better than 1 ppm. Our measurements for the 'coronal lines' are the most accurate yet reported using an EBIT as a spectroscopic source of highly charged ions. These precise wavelength determinations provide a useful test and challenge for atomic structure calculations of many-electron systems.
  • The high-energy electron beam ion trap SuperEBIT at the Lawrence Livermore National Laboratory allows the study of the x-ray emission from highly charged ions interacting with electrons with energy in excess of 200 keV. Radiation from ions as highly charged as Cf96+ has been produced this way. The facility is being used to investigate the contributions from quantum electrodynamics in heavy ions. Here the focus is lithiumlike ions, especially U89+, which provide the opportunity for the most accurate test of QED in highly charged ions. We have also used the facility to measure the degree of x-ray line polarization asmore » a function of the energy of the electron collision energy. For example, we have studied the linear polarization of the K-shell emission lines of Fe24+ for electron-impact energies high as 120 keV. A new area of research is the investigation of nuclear excitation by electronic transitions. This is the inverse process of internal conversion, where an atomic x ray is absorbed by the nucleus resulting in an excited nuclear state. We are planning to study this process in 189Os using 217 keV atomic x rays generated in the interaction with a 196 keV electron beam.« less