| 1. |
- Böhm, S, et al.
(författare)
-
Enhancement of dielectronic recombination by external electromagnetic fields
- 2003
-
Ingår i: Hyperfine Interactions. - 0304-3843. ; 146-147:1-4, s. 23-27
-
Tidskriftsartikel (refereegranskat)abstract
- The enhancement of the dielectronic recombination rate of lithiumlike Ne7+ and O5+ ions by external electromagnetic fields has been measured at the storage ring CRYRING. The energy range covered all 1s(2)2pnl dielectronic recombination resonances attached to the 2s --> 2p core excitation. Electric fields up to 1436 V/cm were applied in the Ne7+ experiment and the saturation of the enhancement with increasing electric field could clearly be seen. In the O5+ experiment the enhancement was studied as a function of the Rydberg quantum number n.
|
|
| 2. |
- Böhm, S, et al.
(författare)
-
Influence of electromagnetic fields on the dielectronic recombination of Ne7+ and O5+ ions
- 2001
-
Ingår i: Physica Scripta. Topical Issues. - 0281-1847. ; T92, s. 395-397
-
Tidskriftsartikel (refereegranskat)abstract
- Within a series of measurements of the dielectronic recombination (DR) of lithium-like ions we have determined the enhancement of the recombination rate in the presence of crossed electric and magnetic fields for Ne7+ and O5+ ions. In both cases the electron energy range covers a DR resonances attached to 2s --> 2p(1/2) and 2s --> 2p(3/2) Delta_n = 0 core excitations. For increasing field the enhancement factor first increases linearly with the electric field and then saturates. In order to investigate the field effect on high-n Rydberg states the ion energy in the O5+ experiment was changed from 9.4 MeV/u to 5 MeV/u and 3.26 MeV/u. With the variation of the ion energy the field ionization of Rydberg states in the analyzing magnet is influenced. This enabled us to study the field enhancement for a narrow bandwidth of n-states.
|
|
| 3. |
- Böhm, S, et al.
(författare)
-
Influence of electromagnetic fields on the dielectronic recombination of Ne7+ ions
- 2001
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 64:3, s. 032707/1-032707/7
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of crossed electric and magnetic fields on dielectronic recombination of Ne7+ ions has been measured at the Stockholm heavy-ion storage ring CRYRING. The electron energy range covered all dielectronic recombination resonances attached to 2s-2p1/2 and 2s-2p3/2 core excitations. Two sets of measurements at magnetic fields of 180 mT and 30 mT have been performed. For the measurement at 180 mT we applied 25 different electric fields between 0 and 1400 V/cm. The resonance strength for dielectronic recombination via high Rydberg states initially increases linearly with electric field and later levels out. At a magnetic field of 30 mT we applied 15 different electric fields ranging from 0 to 140 V/cm. Compared to the measurement at 180 mT the initial slope of the rate enhancement was larger by almost a factor of 2. The fraction of resonant strength not measured due to field ionization is estimated by a model calculation of dielectronic recombination cross sections.
|
|
| 4. |
- Glans, Peter, et al.
(författare)
-
Dielectronic recombination of N4
- 2001
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 649:4, s. 043609/1-043609/11
-
Tidskriftsartikel (refereegranskat)abstract
- The dielectronic recombination spectrum of N4+ has been measured with high resolution and accuracy. The 1s22p5l resonances in the energy range from 0 to 1.6 eV were studied in detail. The experimental spectrum is compared with the results from four different calculations. An almost perfect agreement between the experiment and a calculation which combines relativistic many-body perturbation theory and complex rotation is found. The calculation provides accurate spectroscopic data for all fifty 1s22p5l states. The literature value for the 1s22p5s 1P energy level is found to be off by more than 0.1 eV.
|
|
| 5. |
- Glans, Peter, et al.
(författare)
-
Dielectronic recombination used as a tool for spectroscopic studies of highly charged ions
- 2004
-
Ingår i: Physica scripta. T. - 0281-1847. ; T110, s. 212-215
-
Tidskriftsartikel (refereegranskat)abstract
- Systematic studies of electron-ion recombination for Li-like, Na-like, and Cu-like ions have been made during the last few years at the CRYRING facility. The main purpose has been to measure recombination spectra with such high resolution and accuracy that stringent tests of advanced atomic calculations of doubly excited states can be made. From the comparison with theory it is possible to obtain energy positions, as well as radiative and nonradiative decay rates for the doubly excited states. In addition, for heavy, highly charged ions it is possible to deduce radiative corrections for energy splittings with very high accuracy.
|
|
| 6. |
- Eklöw, N, et al.
(författare)
-
Magnetic-field dependence in electron-deuteron recombination at very low relative energy
- 2000
-
Ingår i: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 127:1-4, s. 251-255
-
Tidskriftsartikel (refereegranskat)abstract
- The rate coefficient for recombination of D+ with low-energy electrons has been measured at different magnetic fields in the interaction region of the electron cooler at CRYRING. It is found that the measured recombination rate coefficient is influenced by the magnetic field.
|
|
| 7. |
- Glans, Peter, et al.
(författare)
-
Dielectronic recombination of Li-like fluorine ions
- 1999
-
Ingår i: Nuclear Instruments & Methods in Physics Research, Section B (Beam Interactions with Materials and Atoms). - 0168-583X. ; 154:1-4, s. 97-101
-
Tidskriftsartikel (refereegranskat)abstract
- Some recent new developments in dielectronic recombination (DR) measurements at heavy-ion storage rings are presented. A DR spectrum measured at CRYRING in Stockholm of F6+ is used to illustrate a few points regarding this kind of measurements. From the spectrum a transversal temperature of the adiabatically expanded electron beam of 3.0(5) meV is deduced, which is slightly higher than expected.
|
|
| 8. |
- Gwinner, G., et al.
(författare)
-
Influence of magnetic fields on electron-ion recombination at very low energies
- 2000
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 84:21, s. 4822-4825
-
Tidskriftsartikel (refereegranskat)abstract
- Radiative recombination (inverse photoionization) is believed to be well understood since the beginning of quantum mechanics. Still, modern experiments consistently reveal excess recombination rates at very low electron-ion center-of-mass energies. In a detailed study on recombination of F and C ions with magnetically guided electrons we explored the yet unexplained rate enhancement, its dependence on the magnetic field B, the electron density n(e), and the beam temperatures T-perpendicular to and T-parallel to. The excess scales as T-perpendicular to(-1/2) and, surprisingly, as T-parallel to(-1/2), increases strongly with B, and is insensitive to n(e). This puts strong constraints on explanations of the enhancement.
|
|
| 9. |
- Hoffknecht, A, et al.
(författare)
-
Recombination of F6+ with free electrons at very low energies
- 1999
-
Ingår i: Physica Scripta. Topical Issues. ; T80B, s. 298-300
-
Tidskriftsartikel (refereegranskat)abstract
- Radiative and dielectronic recombination of F6+ have been studied at the heavy ion storage ring TSR in Heidelberg. For a detailed investigation of rate enhancement effects at very low electron-ion center-of-mass energies experimental parameters such as the magnetic guiding field, the electron density and the adiabatic expansion factor of the electron beam have been varied systematically. Whereas measurements at different electron densities show no influence on the enhancement and while a variation of the expansion factor evokes the predicted behaviour, we see an increase of the enhancement with increasing axial magnetic field between 20 mT and 70 mT.
|
|
| 10. |
- Tokman, M, et al.
(författare)
-
Dielectronic recombination resonances in F6
- 2002
-
Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947. ; 66:1, s. 012703/1-012703/13
-
Tidskriftsartikel (refereegranskat)abstract
- Electron-ion recombination spectra of the Li-like ion F6+ in the energy range 0.0-0.6 eV from two different ion storage rings are presented, showing excellent agreement. The experimental results are compared with a calculated spectrum, obtained by combination of relativistic many-body methods and complex rotation, and the agreement is found to be very good. The recombination spectrum in the studied energy region is determined by the 2p6l dielectronic recombination resonances. The lowest-energy resonances are found around 10 meV, and include one broad resonance overlapping the threshold. The recombination rate coefficients are, even in this region, very well accounted for by the calculation. It is further shown that the nonrelativistically allowed resonances contribute to less than 60% of the integrated rate coefficients in the specified energy range.
|
|
