C. M. Brown,1
J. O. Ekberg,1
U. Feldman,1
J. F. Seely,1
M. C. Richardson,2
F. J. Marshall,2
and W. E. Behring3
1E. O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, D.C. 20375-5000 USA
2Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 USA
3Laboratory for Solar Physics and Astrophysics, Goddard Space Flight Center, Greenbelt, Maryland 20771 USA
J. O. Ekberg is also with Sachs/Freeman Associates, Landover, Maryland 20785; permanent address, Department of Physics, University of Lund, Lund, Sweden.
C. M. Brown, J. O. Ekberg, U. Feldman, J. F. Seely, M. C. Richardson, F. J. Marshall, and W. E. Behring, "Transitions in lithiumlike Cu26+ and berylliumlike Cu25+ of interest for x-ray laser research," J. Opt. Soc. Am. B 4, 533-538 (1987)
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 Å 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 Å 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 Å.
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Intensities based on visual estimates of plate darkening.
Calculated wavelengths of Vainshtein and Safronova.21
Intensities calculated using Klapisch’s computer package for the indicated electron densities (in cm−3). The intensities are normalizedby setting the intensity of the 2p2P3/2–3d2D5/2 transition equal to 25.
Predicted wavelength based on the measured wavelengths of other transitions.
Transitions also observed by Burkhalter et al.22 with a crystal spectrometer during the same laser shots.
Blended with Cu25+ transitions.
Possibly effected by Cu18+ transitions.18
Calculated using the polarization expressions of Edlén.23
Core polarization energy from Edlén.23
Calculated relativistic hydrogenic energy.
Experimentally determined excitation energy.
Ionization energy Ei = Δp + TH + E. The adopted ionization energy is (20 870 ± 3) × 103 cm−1.
Table 4
Wavelengths (in angstroms) and Classification of Spectral Lines for Cu25+
Intensity based on visual estimate of plate darkening.
Calculation using Cowan’s computer program.24
Measured wavelengths and line identifications of Boiko et al.16,17
Calculated wavelengths of Safronova.16,7
Blended with Cu26+ transitions.
Transitions also observed by Burkhalter et al.22 with a crystal spectrometer during the same laser shots.
Multiply classified line.
Blended with Cu22+ transition.
Calculation of Edlén.29
Tables (4)
Table 1
Wavelengths (in angstroms) and Classification of Spectral Lines for Cu26+
Intensities based on visual estimates of plate darkening.
Calculated wavelengths of Vainshtein and Safronova.21
Intensities calculated using Klapisch’s computer package for the indicated electron densities (in cm−3). The intensities are normalizedby setting the intensity of the 2p2P3/2–3d2D5/2 transition equal to 25.
Predicted wavelength based on the measured wavelengths of other transitions.
Transitions also observed by Burkhalter et al.22 with a crystal spectrometer during the same laser shots.
Blended with Cu25+ transitions.
Possibly effected by Cu18+ transitions.18
Calculated using the polarization expressions of Edlén.23
Core polarization energy from Edlén.23
Calculated relativistic hydrogenic energy.
Experimentally determined excitation energy.
Ionization energy Ei = Δp + TH + E. The adopted ionization energy is (20 870 ± 3) × 103 cm−1.
Table 4
Wavelengths (in angstroms) and Classification of Spectral Lines for Cu25+
Intensity based on visual estimate of plate darkening.
Calculation using Cowan’s computer program.24
Measured wavelengths and line identifications of Boiko et al.16,17
Calculated wavelengths of Safronova.16,7
Blended with Cu26+ transitions.
Transitions also observed by Burkhalter et al.22 with a crystal spectrometer during the same laser shots.
Multiply classified line.
Blended with Cu22+ transition.
Calculation of Edlén.29
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