The recent detection of a neutron star merger by the LIGO collaboration has renewed interest in laboratory studies of r-process elements. Accurate modeling and interpretation of the electromagnetic transients following the mergers requires computationally expensive calculations of both the structure and opacity of all trans-iron elements. To date, the necessary atomic data to benchmark structure codes are incomplete or, in some cases, absent entirely. Within the available laboratory studies, the literature on Au I and Au II provides incomplete reports of the emission lines and level structures. We present a new study of Au I and Au II lines and levels by exposing a solid gold target to plasma in the Compact Toroidal Hybrid (CTH) experiment at Auburn University. A wavelength range from 187 to 800 nm was studied. In Au I, 86 lines are observed, 43 of which are unreported in the literature, and the energies of 18 5d9 6s 6p levels and 16 of the 18 known 5d9 6s 6d levels are corroborated by a least-squares level energy optimization. In Au II, 76 emission lines are observed, and 51 of the lines are unreported in the literature. For both Au I and Au II, the new lines predominantly originate from the most energetic of the known levels, and over half of the new Au II lines have wavelengths longer than 300 nm. For the estimated electron parameters of CTH plasmas at the gold target (ne~10^12 cm−3, Te~10 eV), two-electron transitions are similar in intensity to LS-allowed one-electron transitions.
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Panning for Gold: New Emission Lines from UV–VIS Spectroscopy of AuI and AuII
The recent detection of a neutron star merger by the LIGO collaboration has renewed interest in laboratory studies
of r-process elements. Accurate modeling and interpretation of the electromagnetic transients following the
mergers requires computationally expensive calculations of both the structure and opacity of all trans-iron
elements. To date, the necessary atomic data to benchmark structure codes are incomplete or, in some cases, absent
entirely. Within the available laboratory studies, the literature on Au I and Au II provides incomplete reports of the
emission lines and level structures. We present a new study of Au I and Au II lines and levels by exposing a solid
gold target to plasma in the Compact Toroidal Hybrid (CTH) experiment at Auburn University. A wavelength
range from 187 to 800nm was studied. In Au I, 86 lines are observed, 43 of which are unreported in the literature,
and the energies of 18 5d96s6plevels and 16 of the 18 known 5d96s6dlevels are corroborated by a least-squares
level energy optimization. In Au II, 76 emission lines are observed, and 51 of the lines are unreported in the
literature. For both Au I and Au II, the new lines predominantly originate from the most energetic of the known
levels, and over half of the new Au II lines have wavelengths longer than 300 nm. For the estimated electron
parameters of CTH plasmas at the gold target (ne∼1012 cm−3, Te∼10 eV), two-electron transitions are similar in
intensity to LS-allowed one-electron transitions.
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- Award ID(s):
- 1815833
- NSF-PAR ID:
- 10412546
- Date Published:
- Journal Name:
- The Astrophysical journal Supplement series
- Volume:
- 250
- Issue:
- 19
- ISSN:
- 0067-0049
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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