A. Denis

Doubly excited states of lithium

Abstract Three new lines plausibly attributed to doubly excited states are observed in lithium. The mean life of one assigned 1s 2p 2 4 P level is measured to be (0.7 ± 0.2) × 10 -8 sec.

Beam-Foil Study of the 2s22p53l and 2s2p63l Configurations of FeXVII

The spectrum of Fe XVII has been observed in the 200-450 A wavelength range. A total of 31 lines has been measured and classified as transitions between either the 2s22p53s, 3p, 3d configurations or the 2s2p63s, 3p, 3d configurations. Energy levels of these configurations have been deduced and are compared with other available data. The uncertainty in wavelength determinations leads to a precision on energy levels of the order of 150 cm-1 in most cases.

Beam-foil spectroscopy in the extreme UV of highly ionized silicon Si XI and the isoelectronic ions AI X, S XIII and Ar XV

Spectra of highly-ionized silicon, aluminium, sulfur and argon ions produced by the beam-foil technique have been analysed in the 5-40 nm wavelength range. Numerous transitions belonging to n = 3-4, 4-5 and 3-5 transitions arrays in the beryllium-like spectra Al X, Si XI, S XIII and Ar XV were observed for the first time. The assignment of spectral lines was corroborated by comparison along the isoelectronic sequence.

Measurements of 2s-2p Transition Wavelengths in Helium- and Lithium-Like Xenon

We have measured the wavelengths of the 1s2s3S1-1s2p3P2 transition in heliumlike Xe L III and the 1s22s2S1/2-1s22p2P1/2,3/2 transitions in lithiumlike Xe L II. The measurements were made at GANIL by bean-foil spectroscopy of xenon at 27 MeV/u. The wavelength of (26.66 ± 0.10) A for the 2s3S1-2p3P2 transition in Xe L III compares favourably with the most recent calculation, which includes radiative corrections, relativistic correlations and retardation contributions. The results (103.35 ± 0.08) A and (25.18 ± 0.03) A for the Xe L II 2s2S1/2-2p2P1/2,3/2 transition wavelengths are compared to recent theoretical data resulting from multi-configuration Dirac-Fock and many-body perturbation theories.

UV spectroscopy of charge exchange collisions between N5+ ions and H2, He

Abstract We report results concerning a spectroscopic study of radiative transitions observed during the collision between N 5+ ions with H 2 and He. Excitation cross section and their energy variation are measured. In addition to the simple electron capture, strong double electron capture is shown with the He target.

2s-2p Transitions in two-, three- and four-electron copper ions

Abstract We present wavelength measurement of 2s-2p transitions in two-, three-, and four-electron copper ions in beam-foil excited spectra at 10 MeV/amu. Results in beryllium-like Cu 25+ are compared to Edlens semi-empirical data. Our helium-like Cu 27+ 1s2s 3 S 1 − 1s2p 3 P 2 wavelength is compared with calculations including relativistic and radiative contributions. To fit our experimental value a two-electron Lamb-shift correction has to be added. The lifetime of the upper level 2p 3 P 2 has been measured.

Les transitions 2s 3S — 2p 3P des ions heliumoïdes lourds: Cas du Fe XXV

Abstract We present an analysis of our wavelength measurements for the 1s2s 3S1-1s2p 3P2 transition of Fe XXV in beam-foil excited spectra at 6 MeV/u and 7 MeV/u. Results are compared with calculations including the non-relativistic energy, the one-electron Dirac energy, relativistic corrections, the Breit interaction and the one-electron Lamb shift corrections. The present wavelength measurement is sensitive to the Lamb shift contribution alone to a precision of ±3%. We have detailed the limits of accuracy and the relative importance of the Z−p(αZ)q expansion terms of the transition energy for helium-like ions of heavy elements available now or in the near future.

Observation of the resonant lines 2s2S12-2p2P12,32 of lithium-like xenon

Abstract The resonant lines of Xe LII have been observed in a 27 MeV/u xenon beam of GANIL using the beam-foil technique. Incident ions were Xe 50+ , Xe 51+ or Xe 52+ and foil surface densities were 100 μg/cm 2 . The EUV light has been analysed by means of a 2.2 MacPherson 247 grazing incidence spectrometer equipped with a 600 1/mn grating and adjusted at 88° angle. Analysed photons were counted by a position sensitive detector located at the focal plane. By moving this detector to different positions we were able to record spectra in the spectral range 20 to 130 A. The 2 s 2 S 1 2 -2 p 2 P 1 2 and 2 s 2 S 1 2 −2 p 2 P 3 2 lines values are deduced for transition energies and fine structure. The contribution of QED to the 2 s 2 S 1 2 -2 p 2 P 1 2 transition is about 5.2%.

Quantum beat study of the He+ beam-carbon foil interaction

Abstract The quantum beat method is used to measure the HeII ( n =4) populations and coherences in an ion beam accelerated to 0.7–2.2 meV and excited by a carbon foil.

The neonlike spectrum of Kr XXVII

Abstract The spectrum of highly-ionized krypton ions produced by the beam foil technique in the 140–270 A wavelength range has been observed. Lines of neonlike krypton Kr XXVII have been identified by isoelectronic sequence extrapolation and compared with ab initio relativistic calculations. The 2p 5 3 l energy levels have been deduced.