Observations of mercury lines in the HgMn stars χ Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In χ Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure ²⁰⁴Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg II. Observations of mercury in HR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in χ Lupi cannot be explained in this way. Radiative force calculations show that the observed mercury abundance cannot be supported in the atmosphere by the radiative forces alone. We suggest that weak mixing brings mercury into the line-forming region from below the photosphere, while a wind of order 10^-14 M_☉ yr^-1 supports a cloud of Hg III at very small optical depths.

The spectrum of xenon excited in a low-inductance vacuum spark was photographed at high resolution in the region of 9.5–15.5 nm. The observed transitions were identified as belonging to ions from ${\mathrm{Xe}}^{8+}$ to ${\mathrm{Xe}}^{13+}$. In the region of importance for extreme-ultraviolet lithography around 13.4 nm, the strongest lines were identified as $4d^8–4d^{7}5p$ transitions in ${\mathrm{Xe}}^{10+}$. The identifications were made by use of energy parameters extrapolated along the isoelectronic sequence.

New wavelength measurements in the vacuum ultraviolet (VUV), ultraviolet and visible spectral regions have been combined with available literature data to refine and extend the description of the spectrum of singly ionized copper (Cu II). In the VUV region, we measured 401 lines using a concave grating spectrograph and photographic plates. In the UV and visible regions, we measured 276 lines using a Fourier-transform spectrometer. These new measurements were combined with previously unpublished data from the thesis of Ross, with accurate VUV grating measurements of Kaufman and Ward, and with less accurate older measurements of Shenstone to construct a comprehensive list of ≈2440 observed lines, from which we derived a revised set of 379 optimized energy levels, complemented with 89 additional levels obtained using series formulas. Among the 379 experimental levels, 29 are new. Intensities of all lines observed in different experiments have been reduced to the same uniform scale by using newly calculated transition probabilities (A-values). We combined our calculations with published measured and calculated A-values to provide a set of 555 critically evaluated transition probabilities with estimated uncertainties, 162 of which are less than 20%.

We report laboratory measurements to characterize the spectral output of platinum/chromium hollow cathode lamps containing neon carrier gas. The spectra were recorded photographically with the National Institute of Standards and Technology 10.7 m normal-incidence spectrograph. The lamps investigated are equivalent to the lamps used for wavelength calibration of the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Wavelengths and intensities are given for more than 1200 lines in the wavelength range 1132-1827 Å. The uncertainty of the measured wavelengths is estimated to be ±0.0020 Å. During an aging test mimicking the operations on board STIS one Pt/Cr-Ne lamp has passed 1000 hr of operation and is still in excellent working condition. This suggests that such a lamp can be operated for significantly more than 10 years and that it will not be a limiting factor for the useful lifetime of STIS.