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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An experimental setup is described, which is used to multi-ionize neutral clusters and to study their stability and the importance of different decay processes. Clusters are ionized in collisions with slow multiply charged ions (projectile charge z ranging from 1 to 30, kinetic energies ranging from 1 to 20 keV/charge). Both ion and cluster beamlines, as well as the characteristics of the analysis and detection systems, are described. Collisions with highly charged ions such as Ar8+ or Xe30+ turn out to be efficient tools in preparing clusters in high charge states without increasing significantly their internal temperature. Measurements performed in coincidence with the number of electrons stabilized by the projectile ion after the collision allowed us to control the charge and the excitation energy of the ionized system. The efficiency of the method is demonstrated for sodium clusters and C60 molecules. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 317 (1984), S. 139-143 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Single electron capture processes in Ne2+/Ar, Kr collisions were studied by aid of the high-resolution translational spectroscopy. At low collision energies (〈1 keV) the dominant contribution to the Ne+-spectrum arises from Ne2+ ions in the metastable1 S 0-state, although it is the weakest component of the primary Ne2+ beam. Ne2+(3 P) and Ne2+*(1 D) projectiles play no important role due to unfavourable energy defects. Target excitation processes as well as transfer ionisation are considered as a possible explanation for different structures in the measured Ne+ spectra.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 299 (1981), S. 307-309 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At collision energies below 15 keV total charge transfer cross sections have been measured for multiply charged Arζ+(2≦ζ≦6) and Neζ+(2≦ζ≦4) ions colliding with atomic hydrogen. A Wood discharge was used to provide a hydrogen target with a sufficiently high degree of dissociation. Results are compared with measurements performed at higher energies and with theoretical calculations. For ζ=2 cross sections in atomic hydrogen are much smaller than in the molecular case, for ζ〉2 the ratio of these cross sections varies between 0.7 and 1.6.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We have investigated the time dependence of the fragmentation of protonated amino acids stored at 22 keV in the electrostatic ring ELISA. The ions were produced in an electrospray source and after bunching in a quadrupole trap they were excited by collisions in a Ne gas. As in earlier studies of metal clusters and fullerenes produced in “hot” ion sources we find that the dissociation of metastable molecules follows approximately a 1/t decay law until a time $\tau$ after which the yield falls off much more rapidly. We interpret this reduction as a result of radiative cooling with a characteristic cooling time, $\tau_c \simeq G\tau$ , where G is the magnitude of the exponent in an Arrhenius expression for the rate of the dominant fragmentation process. The values of $\tau$ obtained from fits to the data are in the range 9-17 ms corresponding to cooling times of a few hundred milliseconds, in good accord with the expected rate of cooling by emission from IR-active vibrations. The power-law behaviour for $t 〈 \tau$ varies somewhat between the different amino acids, with powers between -0.9 and -1.1. We argue that this may be due to a competition between fragmentation channels with different Arrhenius parameters.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 21 (1991), S. S203 
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new crossed beam apparatus has been developed for measuring differential cross sections for the excitation of multiply charged ions by electron impact. First results have been obtained for sodium-like Argon (Ar7+); the 3s-3p transition with an excitation energy of ∼ 17.5 eV has been studied at an electron energy of 100 eV. The preliminary experimental values are compared with theoretical results obtained within a Born-approximation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 11 (1989), S. 53-61 
    ISSN: 1434-6079
    Keywords: 34.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Single electron capture by triply charged rare gas ions colliding with various rare gas atoms has been studied by means of translational energy spectroscopy (TES) at low collision energies. The final state population is discussed in terms of the so-called reaction window predicted by various models as well as by extended multichannel Landau Zener calculations (MCLZ). The analysis shows the limitations of such model descriptions and yields information on the coupling strength in the case of inner shell capture or multi-electron processes.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 23 (1992), S. 61-66 
    ISSN: 1434-6079
    Keywords: 34.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of excited projectile electrons on the charge exchange mechanism is studied in slow collisions of multiply charged ions with atoms. Translational energy spectra for single electron capture are measured for projectile ions being prepared in the ground state and in an excited metastable state. The differences are discussed in terms of the electron-electron interaction, which turns out to be more important in collision systems with projectiles in low charge states.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 21 (1991), S. S261 
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dissociative electron capture has been studied in low — energetic collisions of multiply charged ions with simple diatomic molecules (H2, D2;E ∼ (1 *q) keV). The different possible capture reactions are separated with the aid of time-of-flight spectra, which are obtained by the coincident measurement of projectile and recoil ions. In particular, we discuss the relative importance of dissociative single electron capture, its dependence on the projectile scattering angle as well as the type of the involved molecular transition.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 21 (1991), S. S271 
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Single electron capture in low-energetic Ar8+ / He collisions has been studied, using projectiles in the (sp6 1So) ground state as well as in the excited (2p5 3P2.0) metastable states. In both cases capture occurs dominantly into the n=4 levels with slightly different 1 — distributions. In the case of the metastable species the relative fractions of the final states which decay by autoionising or by photon emission are discussed and compared with theoretical predictions.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 17 (1990), S. 171-179 
    ISSN: 1434-6079
    Keywords: 34.70 ; 52.20.H
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present spectroscopic measurements of rate coefficients for the population of the ArI 6d[3/2] o and 8s[3/2] o states by two electron transfer from sputtered Cu to Ar2+ in an ECR microwave discharge. Rate coefficients are obtained from absolutely measured line intensities using a modified corona model. Though the binding energies of these states differ by 8 meV only the probability of populating the 6d level exceeds by a factor of ten that of populating the 8s level. This is attributed to an energy resonance between the two electrons when promoting to their final levels. The cross section for this two electron transfer comes out to be of the order of 10−15 to 10−14 cm2.
    Type of Medium: Electronic Resource
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