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  • 11
    Electronic Resource
    Electronic Resource
    Dissociation pathways and binding energies of lithium clusters from evaporation experiments (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6992-7002 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The unimolecular dissociation of energy rich lithium cluster ions shows that Li+n dissociate by sequential atom or dimer loss. The binding energies of Li+n (n=4–42) generated in an evaporative ensemble are determined from unimolecular decay, within a well defined time window, and energy constraint. They present a sawtooth behavior vs cluster size less pronounced that it should be from a simple metal model. Odd–even alternation is superimposed on the sawtooth behavior, with odd sized cluster ions being more stable. Cohesive energies per atom of Li+n are deduced from these dissociation energies up to n=40 and from extended photo-induced measurements up to n=95. Cohesive energies per atom of neutral clusters Lin are derived by combining these ionic cohesive energies with the literature ionization potentials. The linearity of the neutral cluster cohesive energy vs the cluster surface to volume ratio permits a volume and a surface energy to be deduced. These values are compared to the bulk values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468326
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  • 12
    Electronic Resource
    Electronic Resource
    Thermodynamical properties of ionized lithium oxide clusters, Li2n+pO+n (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 6848-6855 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Lithium oxide clusters Li2n+pOn+ are generated by combining reactive nucleation in a gas aggregation source and photoionization. Unimolecular dissociation of mass selected cluster ions provides evidence that the excess of metal atoms evaporates first leading to the most stable species Li+(Li2O)n, which then evaporate Li2O molecules. The evaporation rate behavior as a function of cluster size demonstrates that Li+(Li2O)n can be prepared with different temperatures. It is discussed how metal evaporation from metal-rich oxide clusters leads to oxygen saturated clusters with a lower temperature. An estimate of the dissociation energies of Li+(Li2O)n are given for small sizes n≤10 from photoevaporation experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465829
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  • 13
    Electronic Resource
    Electronic Resource
    Coherent transient phenomena (1982)
    Springer
    Applied physics 29 (1982), S. 179-182 
    Details
    ISSN: 1432-0649
    Keywords: 33 ; 34 ; 36 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688662
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  • 14
    Electronic Resource
    Electronic Resource
    Generation of rare earth metal clusters by means of the gas-aggregation technique (1991)
    Springer
    The European physical journal 19 (1991), S. 195-197 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 35.20 Wg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Generation of rare-earth clusters is achieved using a gas aggregation technique. Varying the nucleation conditions induces a change in the relative cluster abundances. This can be understood in terms of competing cubic versus icosahedron structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448290
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  • 15
    Electronic Resource
    Electronic Resource
    Physical and chemical probes of metallic clusters (1993)
    Springer
    The European physical journal 26 (1993), S. 1-7 
    Details
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two different approaches for studying the electronic structure of clusters are presented. The physical probe uses the photoexcitation of size selected alkali-atom clusters. Giant resonances govern the absorption cross-section. It is due to the collective excitation of delocalized valence electrons. The behavior of the resonance up to large sizes, 900-atom clusters for potassium and 1500-atom clusters for lithium puts into evidence the failure of the jellium model for lithium. The chemical approach makes use of the nucleation process in the presence of oxygen. From the analysis of mass spectra of oxidized products, informations are gained on the valence of metallic atom in the cluster oxide. The method is applied to europium and thulium clusters. A comparison is done with the simple case of alkali clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01429095
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  • 16
    Electronic Resource
    Electronic Resource
    Charge transfer between alkali cluster ions and atoms in the 1 to 10 keV collisional energy range (2000)
    Springer
    The European physical journal 12 (2000), S. 185-192 
    Details
    ISSN: 1434-6079
    Keywords: PACS. 36.40.-c Atomic and molecular clusters - 36.40.Jn Reactivity of clusters - 36.40.Cg Electronic and magnetic properties of clusters - 34.70.+e Charge transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The cross-sections for collisional charge transfer between singly charged free clusters M n + (M = Li, Na; n=1...50) and atomic targets A (cesium, potassium) have been measured as a function of collisional relative velocity in laboratory energy range 1–10 keV. For each cluster size, the experimental values of the charge transfer cross-section are fitted with an universal parametric curve with two independent parameters and vm, the maximum cross-section and the corresponding velocity. For small size clusters ( ), the characteristic parameters show strong variations with the number of atoms in the cluster. Abrupt dips observed for n=10 and n=22 are attributed to electronic properties. Charge transfer patterns observed for various collisional systems present similarities, which appear more sensitive to cluster quantum size effects than to collision energy defects. In their whole, the and vm parameters show differences in both their size evolution and their absolute values discussed in term of projectile and target electronic structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100530070056
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  • 17
    Electronic Resource
    Electronic Resource
    Stability of alkali-atom clusters (1989)
    Springer
    The European physical journal 12 (1989), S. 199-203 
    Details
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A detailed study of the stability of alkali-atom clusters is presented and discussed. Free clusters are produced in an unseeded adiabatic expansion and ionized by a pulsed laser beam. A tandem time-of-flight system provides a size selection of ionized species and mass spectrometry of fragments. We have investigated for sodium and potassium clusters containing up to fifty atoms: the metastable decay following ionization, the photo-induced dissociation, the collisional induced dissociation and the collisional charge exchange. Experimental evidence is shown for dissociative process involving evaporation of monomers and dimers. This is explained by the statistical unimolecular theory and by the energetics of the systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426937
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  • 18
    Electronic Resource
    Electronic Resource
    Charge exchange in alkali cluster collisions (1990)
    Springer
    The European physical journal 17 (1990), S. 61-67 
    Details
    ISSN: 1434-6079
    Keywords: 36.40+d ; 34.70.+e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Collisional charge exchange between mass selected alkali cluster ions and Cs has been studied and cross sections have been determined for the processes Na n + + Cs and K n + + Cs, withn=1–21 andn=1–14, respectively. A strong dependence of the cross sections on the energy defect as well as on cluster size and collision energy is found. The results are analysed by a coupled two state density matrix model, taking account of the relaxation of electronic amplitudes due to interaction with the nuclear motion in the cluster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01437499
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  • 19
    Electronic Resource
    Electronic Resource
    Simple metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 1-6 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 35.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The response of alkali cluster ions to an optical excitation is investigated for two different photon energy domains. Below the ionization potential giant resonances in the photoabsorption cross-section are observed for closed shell species. Above the ionization potential, the ionization process competes with the photofragmentation process. The number of valence electrons determines both the behavior of the photoabsorption spectrum and the evolution of the ionization cross-section with the cluster size. The stability of the clusters against an excess of charge is examined through the observation of an asymmetric fission of Na n ++ . Experimental results are discussed in term of an electrostatic model giving an estimate of the critical size of stability and of the height of the coulombic barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448244
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  • 20
    Electronic Resource
    Electronic Resource
    Evolution of photoionization spectra of metal clusters as a function of size (1986)
    Springer
    The European physical journal 3 (1986), S. 121-129 
    Details
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electronic structure effect in small metallic clusters up ton=15 are investigated through three series of experiments performed on one-valence-electron-atom clusters and two-valence-electron ones. In these experiments the cluster molecular beam is probed by photoionization mass spectroscopy, either by using a tunable laser source for alkali clusters or by synchrotron radiation for mercury ones. With alkali clusters the results are related to fragmentation effects, ionization potential measurements and photoionization efficiency curve profile analysis in the threshold region. The similar behavior of the homogeneous and heterogeneous clusters and the comparison with theoretical models suggest that forn≧3 the valence electrons are partially delocalized. This similarity against the electronic structure is not found in the nucleation process which generates homogeneous and heterogeneous clusters with a strong difference in their respective abundances. For mercury clusters the evolution with size for excitation spectra of two autoionizing lines is obtained up ton=8. Results show that they do not have a metallic character. This is also supported by the observation of small doubly charged mercury clusters forn≧5 which are stable against the Coulomb explosion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01384796
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