J Granzow

Experimental n=3 level lifetimes of Na-like heavy ions in the realm of massive relativistic effects

Abstract The lifetimes of the 3p 2 P° resonance levels and of the 3d 2 D levels in Na-like ions Xe 43+ ( Z = 54) and Au 68+ ( Z = 79) have been measured by time-resolved spectroscopy of foil-excited ion beams. This represents a major step beyond the previous data which reached only up to Z =29, into the range with massive relativistic effects. The results corroborate the lifetimes predicted by very recent calculations of the atomic structure which also reproduce the experimental transition wavelengths.

Time resolved EUV spectroscopy on foil-excited 5.9 MeV/u Xe and 13.2 MeV/u Au ions

N=3, Δn=0 transitions in Na-like ions have been observed and the resonance level lifetimes have been measured by time-resolved spectroscopy of foil-excited ion beams of Xe (Z=54) and Au (Z=79). Other lines in the same wavelength range are identified withn=3, Δn=0 transitions in Ne-, Mg-, and Al-like ions. Wavelengths and transition rates for these new lines are compared to the available theoretical data. A number of experimental problems are discussed.

Beam-foil measurements on intercombination transitions in Cl-like ions of elements Mn through Zn

Prompt and delayed beam-foil spectra have been recorded in the wavelength range of the 3s23p5-3s23p4 3d transitions in Cl-like ions of the elements Mn through Zn. A comparison with simulated spectra reveals the presence of foreign intercombination lines, of ions in neighbouring charge states. For Fe, Ni and Cu a number of decay curves have been recorded at the wavelengths of prominent features in the delayed spectra. The results are compared with available theortical data. A number of solar lines can now be identified with intercombination lines in Cl I-like spectra of Fe and Ni.

Lifetimes of n = 2 levels in foil-excited Kr32+ and Kr33+ ions

Abstract N = 2, Δn = 0 transitions in highly-charged Kr ions have been observed with foil excited ion beams. Decay curves were constructed from delayed multi-channel spectra. Analysis of the decay curves by various techniques which take cascade effects into account yielded n = 2 level lifetimes in the range 10–50 ps. The lifetime results are compared with theoretical predictions for Kr as well as with the isoelectronic trend in the Li and Be isoelectronic sequences.

Extended analysis of intensity anomalies in the Al I isoelectronic sequence

This paper reports an extended experimental investigation, using the beamfoil technique, of the intensity ratio of the fine-structure components in the 3s23p 2P1/2,3/2–3s3p2 2S1/2 and 2P1/2 resonance transitions along the Al I isoelectronic sequence. These intensity ratios are strongly influenced by cancellation/enhancement effects arising from spin-orbit induced level mixings, and are thus sensitive probes of the detailed atomic structure. New data are given for Si II, P III, S IV, K VII, Sc IX, Fe XIV and Ni XVI. Together with previous experimental results this comprehensive isoelectronic study reveals significant and systematic deviations from theoretical predictions.

Experimental transition probabilities of the intercombination line 1s22s2 1S0?1s22s3p 3P10 in Be-like ions of Na through Si

The decay of the 1s22s3p3P00, 1, 2 levels in Be-like ions of Na, Mg, Al and Si has been investigated using the beam-foil method. The mean wavelengths of the transitions 1s22p2 3P0, 1, 2−1s22s3p3P00, 1, 2 and the lifetimes of the 1s22s3p 3P00, 1, 2 levels have been measured. An intercomparison of these lifetimes yields the transition probability of the intercombination line 1s22s2 1S0−1s22s3p 3P10. The results are (3.45 ± 0.73) 109 s−1 in Na VIII, (5.55 ± 0.96) 109 s−1 in Mg IX, (1.21 ± 0.24) 1010 s−1 in Al X and (2.50 ± 0.54) 1010 s−1 in Si XI.

Search for the spectrally narrow radiative decay of 2p3 4So3/2 in He-

Radiative autoionization (RA) of the 2p3 4So state in the He- ion has been predicted to result in a narrow spectral feature near lambda =32.315 nm. The authors have observed a weak, line-like structure at lambda =(32.32+or-0.02) nm, in spectra of foil-excited He ions at incident energies in the range 140-200 keV. This would be the first observation of this elusive RA process. The measurements and supportive evidence are presented as well as preliminary results for electronically similar ions of B and C, in which the decay is taking place connecting bound states, as in the well studied cases of Li and Be.

Beam - foil study of the lifetimes of levels in Na-like Ca X, Mg-like Ca IX and Si-like Ca VII

Levels of Ca ions with one, two or four electrons in the n = 3 shell have been studied for their decay properties and lifetimes. For the levels of Ca X and the level of Ca IX, arbitrarily normalized decay curve (ANDC) and cascade model analyses yield results with precisions of 10% and less and with low systematic uncertainties. The measured lifetime of the Ca IX level confirms the need to include relativistic effects in the calculation. The lifetime results are compared to other, experimental and theoretical, data available for the isoelectronic sequences.

Beam-foil lifetimes measured for intercombination transitions in Zn-like ions of Rh and Ag and Ga-like ions of Rh

Decay curves of the intercombination line 4s2 1S0-4s4p P1o in the Zn-like ions Rh15+ and Ag17+ have been recorded and analyzed for the lifetime of the 4s4p 3P1o level. The new lifetime data for Rh and Ag as well as other recent data for lighter elements are compared to various theoretical predictions. Decay curves measured on the 4s24p 2Po-4s4p2 4P transitions yield the lifetimes of the lowest quartet levels of the Ga-like Rh14+ ion.

Experimental determination of long atomic lifetimes of ions in a storage ring

Abstract Collisions between the circulating ions in an ion storage ring and electrons of an electron cooler can be used for the experimental determination of long atomic lifetimes. Our interest is in the 2s2p 3 P 1 0 level in Be-like ions and the 3s3p 3 5 S 2 0 level in Si-like ions. A time variation of the signal due to ionization of the circulating ions in the residual gas is tentatively used to extract the lifetime of the long-lived excited level in Be-like N 3+ and O 4+ .