J.P. Buchet

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.

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.

VUV Spectra of Multicharged Recoil-Ions: Neon and Argon

The impact of highly charged and high energy ions in a gas target produces excited recoil-ions. The speed of these ions being quite low, the Doppler shifts and broadening of emitted lines are very small. With a Kr20+ beam at 1.15 MeV/amu, we have observed the spectra of Ne ions in the wavelength range 60-570 A and of Ar ions in the range 150-290 A. In the first one, 130 lines have been identified, classified and compared to previous results. In the second one, 55 lines have been observed, 12 transitions unknown up to now are determined and compared to similar transitions for isoelectronic ions. The 3p4d configuration in Ar V is analysed, taking into account the intermediate coupling.

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%.

Beam-foil spectroscopy of nickel and copper at 1.16 MeV/amu

Abstract The beam-foil spectra of nickel and copper obtained at Orsay on the linear injector of the heavy ion accelerator with beams of 1.16 MeV/amu have been analysed in the 110–380 A range. Numerous lines attributed to Ni XVI to XX and Cu XVII to XXI transitions have been identified. The lifetimes of the upper levels of the strongest copper transitions have been measured and are compared with theory and with previous experiments.

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.

Collision induced cluster fragmentation: From fragment size distributions to the caloric curve

We report on a cluster fragmentation study involving collisions of high-energy (60 keV/amu) H3+(H2)m hydrogen cluster ions (m=9, 11) with atomic helium or fullerenes. The experimental characterisation of the cluster fragmentation not only by the average fragment size distribution but also by a statistical analysis of the fragmentation events has become possible owing to a recently developed multi-coincidence technique in which all the fragments of all collisions occurring in the experiment are mass analysed on an event-by-event basis. By selecting specific decay reactions we can start after the energizing collision with a microcanonical cluster ion ensemble of fixed excitation energy. From the respective fragment distributions for these selected decay reactions we derive corresponding temperatures of the decaying cluster ions. The relation between this temperature and the excitation energy (caloric curve) exhibits the typical prerequisites of a first order phase transition in a finite system, in the present case signalling the transition from a bound cluster type situation to the free gas phase.

Beam-Foil Spectroscopy of Highly Ionised C, N, O and Ne Atoms at 1 MeV/Nucleon

Observation and identification of highly stripped transitions in C, N, O and Ne ions are reported. The energy of 1 MeV/nucleon Heavy Ion Linear Accelerator at Orsay is particularly suitable for the beam-foil studies of l-,2- and 3-electron spectra in elements with Z ≤ 10. In the visible and near ultra-violet regions (2500–5500 A) almost all lines are due to hydrogenic transitions for which we know the beam-foil technique is very effective. The resonance lines, the transitions to lower states (n = 2,3) and some doubly excited transitions are observed in the extreme ultra-violet (12 – 300 A) with an improved resolution comparing to our previous published results (1) and an extended spectral range.