W. E. Behring

Spectra of Fe, Co, Ni, and Cu Isoelectronic with Na i and Mg i

Highly ionized spectra of Fe, Co, Ni, and Cu belonging to the Na I and Mg I isoelectronic sequences are discussed. For the Na I-type spectra about 48 lines between 20 and 400 A are classified for the first time. The wavelengths of some 20 other previously classified lines are given with greater accuracy. The measurement of the n = 3 transitions and of the higher-series lines has enabled us to construct the energy-level table and to obtain accurate least-square fits for the series limits and ionization potentials. For the Mg I sequence, nine new lines are classified in Fe xv and Co xvi and 36 lines in Ni xvii and Cu xviii. Not enough lines are yet classified to deduce the values of the energy levels.

Transitions in Fe-, Co-, Cu-, and Zn-like ions of W and Re

The spectra of highly ionized W and Re were observed by using laser-produced plasmas and a 3-m grazing-incidence spectrograph. Transitions in Fe- through Zn-like ions were identified. Wavelengths in the range 7–75 A were measured with an uncertainty of ±0.015 A, and energy levels were derived from the measured wavelengths. The ionization limits of Cu-like W and Re were determined.

Laser-plasma spectra of highly ionized fluorine

Lines between 11.3 and 17.2 A of lithium-like, helium-like, and hydrogen-like fluorine have been observed in spectra of laser-produced plasmas. These lines include nine members of the Lyman series of F IX; eight members of the principal series of F VIII; and satellite lines arising from doubly excited configurations of F VII and F VIII. Similar satellite lines of the abundant solar elements have been identified in soft X-ray spectra of solar flares. A wavelength list of fluorine lines is given, and physical conditions in the plasma are discussed.

Transitions in lithiumlike Cu 26+ and berylliumlike Cu 25+ of interest for x-ray laser research

Transitions in highly charged copper ions have been identified in the extreme-ultraviolet spectra from plasmas produced by the Omega laser at the University of Rochester. The 24 beams of the Omega laser were focused to separate spots of diameter 50 μm upon the surface of copper-coated targets 600 μm in diameter. The transitions in lithiumlike Cu26+ and berylliumlike Cu25+ of the type n = 3–4 were observed in the wavelength region 24 to 28 A and were bright in the focal regions. The intensities of the Cu26+ 2p–3d and 3d–4f transitions indicate that a population inversion occurs between the 3d and 4f levels. Comparisons of the observed relative intensities of the Cu26+ transitions with calculated intensities indicate that the Cu26+ spectrum originates in a plasma region with an electron density of order of 1020 cm−3 and that collisional recombination is important for populating the 4f level. The 3d–4f transitions at 25.525and 25.636 A in Cu26+, and the same transitions in neighboring elements, appear to be good candidates for achieving gain at wavelengths below the carbon absorption edge at 43.5 A.

Wavelengths and energy levels for the Na I isoelectronic sequence Y28+ through U81+

Abstract Na-like transitions from the n = 3, 4, and 5 excited levels of the ions Cd 37+ , In 38+ , Sn 39+ , and Gd 53+ were identified in the extreme ultraviolet spectra from plasmas produced by one or two beams of the Nova laser at the Lawrence Livermore National Laboratory. The currently observed wavelengths and the previously observed wavelengths for lower Z ions were compared with the wavelengths calculated using Grants multiconfiguration Dirac-Fock program. Based on this comparison, semiempirical corrections to the wavelengths were made, and the corrected wavelengths were determined for the ions Y 28+ through U 81+ . The excitation energies for the n = 3, 4, and 5 levels and the ionization energies of the ground states were also derived for the ions Y 28+ through U 81+ .

Transitions of the type 2s–2p in highly ionized Cu, Zn, Ga, and Ge

Transitions of the type 2s–2p in the F i, O i, N i, and C i isoelectronic sequences of copper, zinc, gallium, and germanium have been identified in the spectra from plasmas produced by the omega laser system at the University of Rochester. The wavelengths are in the range 50 to 112 A and are measured using silicon and oxygen lines as wavelength standards for gallium and using several lines from the F i, O i, and Na i isoelectronic sequences as wavelength standards for copper, zinc, and germanium. The energy levels that are determined from the measured wavelengths are also presented. Based on these measurements, the wavelengths for a number of magnetic-dipole transitions within the ground configurations of the F i, O i, and N i isoelectronic sequences are predicted.

Spectra of Mg ix, Al x, and Si xi Isoelectronic with Be i

In this work, we extend the previous analysis of the Mg ix, Al x, and Si xi spectra. Classifications and wavelengths are given for 90 new transitions in the range 30–60 A. Wavenumbers are given for 60 new levels. The analysis is given for several cases of unresolved spectral lines. The term structure of these ions is discussed and term values are given for several experimentally uncorrelated groups of terms.

Lithium-Like Spectra in Mg, Al, and Si

Using a grazing-incidence spectrometer and a low-inductance 14-μF, 12–15-kV spark source, we have observed spectra of Mg x, Al xi, and Si xii. About 50 new lines are reported between 25 and 65 A, arising from transitions between the lowest 2s and 2p configurations and ns, np, and nd configurations, where n≥3.

Transitions of Zn xxii, Zn xxiii, Zn xxiv, Ge xxiv, and Ge xxv observed in laser-produced plasmas

Wavelengths and energy levels are given for zinc lines of the F i, O i, and N i isoelectronic sequences, and for germanium lines of the F i and O i sequences, for transitions of the type 2s22pk–2s2pk+1. These lines were observed just below 100 A in spectra of laser-produced plasmas. Copper and gallium lines are interpolated using the zinc and germanium wavelengths and the lines of nickel previously reported. The derived energy levels in the F i and O i sequences for zinc and germanium are compared with semiempirical predictions of Edlen.

Spectra and energy levels of Sm XXXIV, Eu XXXV, Gd XXXVI, and Yb XXXXII

We present wavelengths and energy levels based on extreme-ultraviolet and x-ray transitions in the ions Sm+33, Eu+34, Gd+35, and Yb+41 of the cu i isoelectronic sequence. The sources of the spectra were laser-produced plasmas generated by the OMEGA laser facility at the University of Rochester’s Laboratory for Laser Energetics. The photographic spectra were recoreder by a 3-m grazing-incidence spectograph. The spectra lines fall between about 10 and 115 A and we compare our results with previous measurements where available.