At the Livermore electron-beam ion-trap facility, extreme-ultraviolet spectra of tungsten have been recorded in the wavelength range 40–85 Å. The electron-beam energy was varied systematically to identify the individual spectra of Rb-like W37+ to Cu-like W45+. About 60 spectral features have been identified. PACS Nos.: 32.30Rj, 39.30+w, 31.50+w

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We report on emission spectra of iron in the extreme ultraviolet recorded at an electron density of $5 Â 10 11 cm À3 at the Lawrence Livermore electron beam ion trap EBIT-II. We present a summary of observed emission lines, including wavelengths and emission intensities. We also illustrate our technique for isolating pure charge states of the desired ion and present spectra of pure Fe vii-Fe x. Our measurements add a large number of newly identified lines to existing line lists in the extreme-ultraviolet region, 60-140 Å . While many of these lines are quite weak, they add up to a significant flux that can seriously affect interpretations of global fitting models, especially when applied to stars with material at the appropriate temperatures, such as Procyon, Cen, and the Sun.

Transition probabilities of three magnetic dipole (M1) transitions in multiply charged ions of Ar have been measured using the Livermore electron-beam ion trap. Two of the transitions are in the ground conÐgurations of Ar XIV (B-like) and Ar IX (F-like), and are associated with the coronal lines at 4412.4 and 5533.4respectively. The third is in the excited 2s2p conÐguration of Be-like Ar XV and produces A , the coronal line at 5943.73Our results for the three atomic level lifetimes are 9.32^0.12 ms for the A . Ar X 2s22p5 level, 9.70^0.15 ms for the Ar XIV 2s22p level, and 15.0^0.8 ms for the Ar XVlevel. These results di †er signiÐcantly from earlier measurements and are the most accurate 3P 2 o ones to date.

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Articles you may be interested inExtended-range grazing-incidence spectrometer for high-resolution extreme ultraviolet measurements on an electron beam ion trapa) Rev. Sci. Instrum. 85, 11E422 (2014);Highly charged metal ions produced from volatile organometallic compounds in a room temperature electron beam ion trap Rev.High energy operation of the Tokyo-electron beam ion trap/present status Rev. Sci. Instrum. 71, 687 (2000)A compact grazing-incidence spectrometer was implemented on the Livermore electron beam ion trap facility for spectral measurements in the extreme ultraviolet spectral region. The spectrometer employed a 1200 l /mm grating designed for flat-field focusing and a charge coupled device camera for readout. The instrument was used to measure line emission in the range from 25 to 220 Å with a resolving power as high as 600. The performance and calibration of the instrument is described and spectra from highly charged nitrogen and iron ions are presented. Measurements of the K-shell spectrum of He-like N 5ϩ are presented that confirm earlier wavelength determinations and illustrate the accuracy achievable with the instrument. Our measurement suggests a change in the line identifications of the forbidden He-like N 5ϩ transition 1s2s 3 S 1 →1s 2 1 S 0 and of the Li-like N 4ϩ collisional satellite transition 1s2s2p 2 P 3/2 →1s 2 2s 2 S 1/2 observed on the Alcator C-Mod tokamak.

Optical measurements of a clean, 2-mC 233 U sample were made to verify light emission from gamma ray decay of the first excited nuclear level in 229 Th. The results showed that the light observed in earlier studies was likely to be caused by alpha-particle induced fluorescence of air. In vacuo, no light emission was discernable. The 229 Th system, therefore, does not appear to provide the level of access for studying atomic-nuclear interactions suggested by the previous measurements. [ S0031-9007(98)08232-5] PACS numbers: 23.20.Lv, 27.90. + b, 32.30.Jc Interactions between the nuclear and atomic systems have attracted considerable attention because of the potential of stimulating nuclear transitions by laser excitation of atomic states. In the inelastic bridge mechanism, for example, nuclear deexcitation is coupled to atomic excitation. In particular, an electromagnetic nuclear transition couples to an atomic electron, which is elevated to an excited state, thereby reducing the energy of the final gamma ray [1-3]. The mechanism suggests that the inverse may be possible, i.e., that atomic deexcitation may induce nuclear excitations [4]. Nuclear excitation energies, however, are generally much larger than atomic excitation energies. The identification of cases where the energies are comparable is, therefore, of highest importance.The nuclear spectroscopy of high-energy gamma rays from 229 Th produced in the alpha decay of 233 U suggests that the ground state is a closely spaced doublet separated by 3.5 eV [5][6][7]. The energy of the first excited level, thus, is lower than any other known excited nuclear level. Recently, Irwin and Kim reported the detection of photon emission resulting from the deexcitation of the 229 Th isomer [8]. The energy of the observed photons was determined to be about 3.5 6 1.0 eV, in agreement with the value inferred indirectly from the nuclear spectroscopy of the high-energy gamma rays. Moreover, one of two samples of 233 U studied showed a second photon peak near 2.4 eV [8]. The observation of this peak was consistent with predictions that the inelastic bridge mechanism could cause excitation of the thorium atom from the 6d 3͞2 ground level to the 7p 1͞2 excited level. The Letter suggested that 229 Th provides a perfect isotope for future studies of low-energy nuclear-atomic interactions since the energy spacing is well within the realm of present-day laser capabilities.A subsequent study by Richardson et al.[9] also observed emission in the UV. Employing a higher resolution spectrograph than Irwin and Kim, they were able to discern three peaks near 3.5 eV. Their result, thus, appeared to confirm the measurement of Irwin and Kim.In the following we present experimental studies of the optical emission of a clean sample of 233 U decaying to 229 Th. We found no evidence for the optical emission attributable to the deexcitation of the predicted low-lying 229 Th isomer. We found light caused by alpha-particle induced fluorescence of air. In the absence of air, no light emission was di...

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