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  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopy of the 1 2Πu state of Na+2 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 4030-4038 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report here the first experimental observation of bound–bound transitions between the ground X 2Σ+g and excited 1 2Πu states of Na+2. The basis of our experiment is to study doubly excited Rydberg states of Na2 by preparing a well-defined nd 1Λg singly excited Rydberg state of Na2 and then, by exciting the Na+2 core with a tunable laser. In this paper, we show that the ionic transitions may be directly deduced from the doubly excited Rydberg states spectra [C. Bordas, J. L. Vialle, and M. Broyer (submitted)]. We demonstrate that this technique is one of the most powerful to study the excited states of diatomic ions which are not predissociated. A detailed spectroscopic analysis of the 1 2Πu state has been performed and the results are compared with the more recent ab initio and pseudo- (or model-) potential calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457816
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  • 2
    Electronic Resource
    Electronic Resource
    Coating and polymerization of C60 with carbon: A gas phase photodissociation study (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 3088-3097 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: (C60)nCq+ cationic clusters are produced in a laser vaporization source by quenching the vapors from C60 and graphite targets. They are analyzed in the gas phase by abundance and photofragmentation time-of-flight mass spectroscopy. Among the large number of expected isomers, the present experiments give evidence for the stability of special arrangements that may result from the attachment of preformed carbon rings to the fullerene cage. The particular case of C10 will be discussed, considering the results obtained on complexes with one, two or even three C60 molecules. This study reveals that the incorporation of large molecules into carbon cages could be an essential mechanism during the growth process of larger fullerenes and that the polymerization of C60 molecules is promoted by carbon links involving a single atom or a dimer. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1494780
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  • 3
    Electronic Resource
    Electronic Resource
    Gas phase study of silicon–C60 complexes: Surface coating and polymerization (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8436-8445 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: (C60)nSim+ cationic clusters are produced in a laser vaporization source by quenching the vapors from two independent C60 and silicon targets. They are analyzed in the gas phase by abundance and photofragmentation time-of-flight mass spectroscopy. For complexes containing only one C60 molecule, silicon is unlikely to wet the fullerene surface. Mass spectroscopic studies are rather in favor of a three-dimensional growth of silicon clusters weakly bound to C60. For larger systems, one can distinguish two classes of silicon atoms: most of them group in the form of compact islands (or clusters) and some others are directly involved in the linkage of C60 molecules. Particular geometric structures for the stable polymers (C60Si)n−2(C60)2+, (C60Si)n−1C60+, and (C60Si)n+ are postulated. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481447
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  • 4
    Electronic Resource
    Electronic Resource
    Study of bimetallic Pd–Pt clusters in both free and supported phases (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 8574-8585 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We study PdPt bimetallic clusters in both free and supported phases. These clusters have been produced with a laser vaporization source. Free clusters directly produced by the source are studied by time of flight mass spectrometry and photofragmentation technique. We observed a sequential evaporation of Pd atoms in the mixed clusters consistent with a palladium segregation process. This tendency has been also observed on supported particles from which the structure and the composition are determined by high resolution transmission electron microscopy and energy dispersive x-ray analysis. A main result is that each particle has the composition of the massic rod vaporized in the source. The supported particles are well crystallized and exhibit truncated octahedron shapes. Experimental observations are well explained using a modified tight binding model. Indeed, within this model, we found that the equilibrium shape is strongly related to the variation of the cohesive energy with atomic coordination number. Also, some preliminary results on the specific reactivity of these bimetallic clusters are presented. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468847
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  • 5
    Electronic Resource
    Electronic Resource
    Competition between atomic shell and electronic shell structures in aluminum clusters (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 754-755 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Under usual experimental conditions, aluminum clusters have specific geometric arrangement. By heating the nozzle, we obtain melted aluminum clusters, and a new periodicity appears in mass spectra, which corresponds to electronic shells up to 1800 electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466894
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  • 6
    Electronic Resource
    Electronic Resource
    Photolysis experiments on SiC mixed clusters: From silicon carbide clusters to silicon-doped fullerenes (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 6927-6938 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Silicon carbon binary clusters are generated in a laser vaporization source from SixC1−x mixed targets (x=0 to 50%). We have first analyzed stoichiometric (SiC)n (n≤40) clusters grown from a silicon carbide target (x=50%). Both high fluence photoionization of (SiC)n neutral clusters and photofragmentation of size-selected (SiC)n+ natural positive ions show that silicon-doped fullerenes emerge as stable photoproducts through the laser induced annealing of these clusters. They are detected as stable species as soon as a sufficient amount of silicon is eliminated through unimolecular processes involving the sequential losses of Si2C and Si3C neutral molecules in the earliest evaporation steps. This result is in favor of an efficient substitution of silicon atoms (about 12) into stable "cagelike" carbon networks. We will also show that an efficient doping of carbon fullerenes with silicon atoms can be obtained in carbon-rich mixed clusters directly grown as positive ions from nonstoichiometric targets (x〈25%). Mass abundance spectroscopy gives a clear signature of cagelike structures where silicon atoms are substituted for carbon ones. The results on the favored stability of even-numbered C2n−qSiq+ clusters with q=0, 1, 2 are presented here in the size range: 2n=32–80. More largely doped species (q≥3) cannot be evidenced in abundance mass spectroscopy because of unavoidable mass coincidences. A careful analysis of the photofragmentation behavior of selected sizes relative to the laser fluence nevertheless succeeds in indicating the contribution to the photofragmentation spectra of largely doped heterofullerenes C2n−qSiq+ (q=7 at least) that mainly dissociate by the loss of small even-numbered mixed molecules such as Si2,Si3C,... . Both approaches are consistent with the surprising capability of substituting a large number of silicon atoms into fullerenes without destabilizing their cage structure too much. In this respect, a value close to 12 seems to be an upper limit. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478598
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  • 7
    Electronic Resource
    Electronic Resource
    Unimolecular dissociation of trivalent metal cluster ions: The size evolution of metallic bonding (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 757-771 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The unimolecular decomposition of size selected cluster cations of trivalent metals (Aln+, Gan+, and Inn+), induced by high fluence laser ionization, has been investigated in the n=7 to n=85, 55, and 75 size ranges, respectively. This method is applied for the first time to photoexcited trivalent clusters generated in an evaporative ensemble and the experimental data cover a size range that was not explored in previous pioneering experiments on their dynamics. Small clusters dissociate through the loss of a neutral or a charged atom whereas clusters larger than a well defined critical size merely dissociate through the first channel. In the framework of the RRK statistical theory, the measured evaporation rates provide some information about the size evolution of the cluster dissociation energies and their ionization potentials in the low size range. The competition between the ion and the atom evaporation is found to be consistent with the size evolution of the ionization potentials independently measured by direct photoionization. The agreement between theory and experiment is discussed in relation to cluster structure, especially in the case of gallium. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474374
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  • 8
    Electronic Resource
    Electronic Resource
    Shell structure in photoionization spectra of large aluminum clusters (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 944-950 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photoionization mass spectrometry experiments, performed on an extensive size range of aluminum clusters produced by laser vaporization technique, are reported. Ionization potential values are deduced from individual photoionization efficiency curves for the smaller AlN clusters (N=36–112). Our results confirm and complete those previously published. The mass spectra of larger clusters (N≈250–1400) reveal a regular signal oscillation. Several additional experiments give proof that this striking pattern originates from size-dependent ionization threshold effects. This structure exhibits exact periodicity as a function of N1/3 or Ne1/3 (Ne the number of valence electrons).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464257
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  • 9
    Electronic Resource
    Electronic Resource
    A cylindrical reflectron time-of-flight mass spectrometer (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 2312-2318 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new reflectron time-of-flight mass spectrometer with a cylindrical electrostatic mirror instead of the usual plane reflector is described. When it is mounted at right angles to the direction of an incoming molecular beam, this system automatically compensates for the transverse drift of the ions in the spectrometer due to their initial velocity parallel to the molecular beam direction. As a consequence, ions of any mass can be collected onto the detector, whatever their initial transverse velocity is. The mass range accessible in a single scan with our cylindrical reflectron is thus strongly increased as compared to the case of a usual plane reflectron. This article presents the general design of our cylindrical reflectron. A detailed description of the apparatus is given and its performances are illustrated on selected examples. Cluster mass spectra extending over a very wide size range are presented. A mass resolution of about 4000 is achieved in mass spectra of laser photoionized aluminum clusters. Moreover, the cylindrical geometry of the reflector gives rise to focusing properties onto the detector, which could be interesting in view of collection efficiency improvement. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148141
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  • 10
    Electronic Resource
    Electronic Resource
    Atomic-beam deflection and broadening by recoils due to photon absorption or emission
    Amsterdam : Elsevier
    Optics Communications 5 (1972), S. 402-406 
    Details
    ISSN: 0030-4018
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0030-4018(72)90043-0
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