| 1. |
- Böhm, S, et al.
(författare)
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Enhancement of dielectronic recombination by external electromagnetic fields
- 2003
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Ingår i: Hyperfine Interactions. - 0304-3843. ; 146-147:1-4, s. 23-27
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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.
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| 2. |
- Böhm, S, et al.
(författare)
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Influence of electromagnetic fields on the dielectronic recombination of Ne7+ and O5+ ions
- 2001
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Ingår i: Physica Scripta. Topical Issues. - 0281-1847. ; T92, s. 395-397
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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.
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| 3. |
- Böhm, S, et al.
(författare)
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Influence of electromagnetic fields on the dielectronic recombination of Ne7+ ions
- 2001
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 64:3, s. 032707/1-032707/7
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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.
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| 4. |
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| 5. |
- Aberg, J, et al.
(författare)
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Electrical properties of the TiSi2-Si transition region in contacts : The influence of an interposed layer of Nb
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:5, s. 2380-2388
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Tidskriftsartikel (refereegranskat)abstract
- The influence of an interposed ultrathin Nb layer between Ti and Si on the silicide formation and the electrical contact between the silicide formed and the Si substrate is investigated. The presence of the Nb interlayer results in the formation of ternary alloy (Nb,Ti)Si-2 in the C40 crystallographic structure adjacent to the Si substrate. Depending on the nature of the Si substrates and/or the amount of the initial Nb, the interfacial C40 (Nb,Ti)Si-2 leads, in turn, to either epitaxial growth of a highly faulted metastable C40 TiSi2 or formation of the desired C54 TiSi2 at a lower temperature than needed for it to form in reference samples with Ti deposited directly on Si. On p-type substrates doped to various concentrations, the Nb also leads to a considerably lower specific contact resistivity than that obtained in the reference samples: a twofold to fourfold reduction in the contact resistivity is found using cross-bridge Kelvin structures in combination with two-dimensional numerical simulation. As C40 (Nb,Ti)Si-2 forms at the interface when an interfacial Nb is present, the interface characterized is likely to represent the one between (Nb,Ti)Si-2 and Si. For the reference samples, the interface studied is between TiSi2 and Si.
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| 6. |
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| 7. |
- Cooper, K., et al.
(författare)
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New Grid Scheduling and Rescheduling Methods in the GrADS Project
- 2004
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Konferensbidrag (refereegranskat)abstract
- Summary form only given. The goal of the Grid Application Development Software (GrADS) project is to provide programming tools and an execution environment to ease program development for the grid. We present recent extensions to the GrADS software framework: 1. A new approach to scheduling workflow computations, applied to a 3D image reconstruction application; 2. A simple stop/migrate/restart approach to rescheduling grid applications, applied to a QR 3. A process-swapping approach to rescheduling, applied to an N-body simulation. Experiments validating these methods were carried out on both the GrADS MacroGrid (a small but functional grid) and the MicroGrid (a controlled emulation of the grid) and the results were demonstrated at the SC2003 conference.
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| 8. |
- Hellberg, Per-Erik, et al.
(författare)
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Threshold voltage control for PMOSFETs using an undoped epitaxial Si channel and a p(+)-SixGe1-x gate
- 2000
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Ingår i: Solid-State Electronics. - 0038-1101 .- 1879-2405. ; 44:11, s. 2085-2088
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines experimentally the performance of PMOSFETs with an undoped epitaxial Si channel in combination with a p(+)-SixGe1-x gate electrode. The channel doping profiles were made using shallow As-implantation followed by selective epitaxy of undoped Si to different thicknesses of 40, 80 and 120 nm. The p(+)-SixGe1-x gate with different values of x was used to tailor the threshold voltage. The transconductance and saturation current were found to increase and the threshold voltage to decrease with increasing thickness of the undoped Si channel for the same gate material. Increasing Ge content in the p(+)-SixGe1-x gate resulted in an increased threshold voltage. Compared to the p(+)-Si gate, the threshold voltage was increased by 0.15 and 0.35 V with a p(+)-Si0.79Ge0.21 and p(+)-Si0.53Ge0.47 gate, respectively, independently of the Si channel thickness. Therefore, the use of a p(+)-SixGe1-x gate introduces an extra degree of freedom when designing the channel for high performance PMOSFETs.
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| 9. |
- Liu, T. B., et al.
(författare)
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Synthesis, structures and electrochemical properties of nitro- and amino-functionalized diiron azadithiolates as active site models of Fe-only hydrogenases
- 2004
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 10:18, s. 4474-4479
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Tidskriftsartikel (refereegranskat)abstract
- Complex [{(mu-SCH2)(2)N(4-NO2C6H4)}Fe-2(CO)(6)] (4) was prepared by the reaction of the dianionic intermediate [(mu-S)(2)Fe-2(CO)(6)](2-) and N,N-bis(chloromethyl)-4-nitroaniline as a biomimetic model of the active site of Fe-only hydrogenase. The reduction of 4 by Pd-C/H-2 under a neutral condition afforded complex [{(mu-SCH2)(2)N(4-NH2C6H4)}Fe-2(CO)(6)] (5) in 67% yield. Both complexes were characterized by IR, H-1 and C-13 NMR spectroscopy and MS spectrometry. The molecular structure of 4, as determined by X-ray analysis, has a butterfly 2Fe2S core and the aryl group on the bridged-N atom slants to the Fe(2) site. Cyclic voltammograms of 4 and 5 were studied to evaluate their redox properties. It was found that complex 4 catalyzed electrochemical proton reduction in the presence of acetic acid. A plausible mechanism of the electrocatalytic proton reduction is discussed.
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| 10. |
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