13 research outputs found
A Laser System for the Spectroscopy of Highly-Charged Bismuth Ions
We present and characterize a laser system for the spectroscopy on
highly-charged ^209Bi^82+ ions at a wavelength of 243.87 nm. For absolute
frequency stabilization, the laser system is locked to a near-infra-red laser
stabilized to a rubidium transition line using a transfer cavity based locking
scheme. Tuning of the output frequency with high precision is achieved via a
tunable rf offset lock. A sample-and-hold technique gives an extended tuning
range of several THz in the UV. This scheme is universally applicable to the
stabilization of laser systems at wavelengths not directly accessible to atomic
or molecular resonances. We determine the frequency accuracy of the laser
system using Doppler-free absorption spectroscopy of Te_2 vapour at 488 nm.
Scaled to the target wavelength of 244 nm, we achieve a frequency uncertainty
of \sigma_{244nm} = 6.14 MHz (one standard deviation) over six days of
operation.Comment: Contribution to the special issue on "Trapped Ions" in "Applied
Physics B
Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps
A newly constructed apparatus at the National Institute of Standards and
Technology (NIST) is designed for the isolation, manipulation, and study of
highly charged ions. Highly charged ions are produced in the NIST electron-beam
ion trap (EBIT), extracted through a beamline that selects a single mass/charge
species, then captured in a compact Penning trap. The magnetic field of the
trap is generated by cylindrical NdFeB permanent magnets integrated into its
electrodes. In a room-temperature prototype trap with a single NdFeB magnet,
species including Ne10+ and N7+ were confined with storage times of order 1
second, showing the potential of this setup for manipulation and spectroscopy
of highly charged ions in a controlled environment. Ion capture has since been
demonstrated with similar storage times in a more-elaborate Penning trap that
integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing
experiments utilize a second-generation apparatus that incorporates this
two-magnet Penning trap along with a fast time-of-flight MCP detector capable
of resolving the charge-state evolution of trapped ions. Holes in the
two-magnet Penning trap ring electrode allow for optical and atomic beam
access. Possible applications include spectroscopic studies of one-electron
ions in Rydberg states, as well as highly charged ions of interest in atomic
physics, metrology, astrophysics, and plasma diagnostics.Comment: Proceedings of CDAMOP-2011, 13-16 Dec 2011, Delhi, India. To be
published by Springer Verla
EUV magnetic-dipole lines from highly-charged high-Z ions with an open 3d shell
The electron beam ion trap (EBIT) at the National Institute of Standards and Technology
was used to produce highly-charged ions of hafnium, tantalum and gold with an open
3d shell. The extreme-ultraviolet (EUV) spectra from these ions were
recorded with a flat-field grazing-incidence spectrometer in the wavelength range of
4.5Â nm to 25Â nm. A total of 133 new spectral lines, primarily due to magnetic-dipole
transitions within the ground-state 3dn
configurations of the Co-like to K-like ions, were identified by comparing
energy-dependent experimental spectra with a detailed collisional-radiative modeling of
the EBIT plasma
Absolute photoionization cross sections for Xe<sup>4+,</sup> Xe<sup>5+</sup>, and Xe<sup>6+</sup> near 13.5 nm: Experiment and theory
Separation of inner shell vacancy transfer mechanisms in collisions of slow Ar17 ions with SiO2
UTA versus line emission for EUVL : studies on xenon emission at the NIST EBIT
Spectra from xenon ions have been recorded at the NIST EBIT and the emission into a 2% bandwidth at 13.5 nm arising from 4d_5p transitions compared with that from 4d_4f and 4p_4d transitions in Xe XI and also with that obtained from the unresolved transition array (UTA) observed to peak just below 11 nm. It was found that an improvement of a factor of five could be gained in photon yield using the UTA rather than the 4d_5p emission. The results are compared with atomic structure calculations and imply that a significant gain in efficiency should be obtained using tin, in which the emission at 13.5 nm comes from a similar UTA, rather than xenon as an EUVL source material.Science Foundation Irelan