Observation of clusters in a sputtering ion source

Herzog, R.; Poschenrieder, W.; Satkiewicz, F. G.

doi:10.1080/00337577308232122

Cited by 96 publications

(8 citation statements)

References 11 publications

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“…Secondary ions were accelerated to a nominal energy of 4.5 keV and filtered by an electrostatic sector and a magnetic analyzer. Herzog et al [1973] have shown that secondary molecular ions (dimers, oxides, hydrides, etc.) have distinctly lower initial kinetic energy when leaving the sample surface than monoatomic species and that these undesirable molecular ions can be eliminated from the secondary ion mass spectrum by reducing the secondary accelerating voltage by an amount comparable to their initial kinetic energy.…”

Section: Ion Microprobe Techniquesmentioning

confidence: 99%

Effects of silicate liquid composition on mineral‐liquid element partitioning from Soret diffusion studies

Lesher¹

1986

J. Geophys. Res.

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Thermal (Soret) diffusion of major, minor, and trace components of naturally occurring silicate melts ranging in composition from tholeiitic basalt to high-silica rhyolite is examined at 1 GPa, mean temperatures of 1380ø-1535øC, and temperature gradients of 50ø-80øC mm-x. Soret diffusion in silicate melts is channeled along network former/network modifier compositional vectors indistinguishable from those observed in silicate liquid immiscibilty studies, but in the former case, gradients are continuous between the compositional (and thermal) extremes. Si, the chief network former, invariably segregates to the hot end of the temperature gradient as do Rb, K, and Na in melts of mafic to intermediate bulk composition. and Ti always show separations antithetic to Si, while Rb, K, and Na fractionate from Si only in silicic melts. Li and A1 display little separation in a temperature gradient. Soret separations of alkali and alkaline earth cations are consistent with their participation in the network as charge compensators for trivalent network formers (i.e., A13+, etc.). These network formers as well as network modifiers show fractionations from Si that depend directly on cation field strength and size, and the polymerization state of the melt. Temperature and absolute concentration have no measurable effect on the fractionation behavior of these components relative to that of SiO 2, the principal determinant of melt structure. The melt compositional dependence of element partitioning is characterized using these data. Twofold to fourfold changes in mineral-liquid partition coefficients for minor and trace elements are expected over the melting range for typical basalts, and similar or greater variabilty is expected during differentiation of silicic magmas. These expectations corroborate reported variability of mineral-liquid partition coefficients from studies of natural igneous rock samples and experimental phase equilibria. INTRODUCTION Basic to our understanding of the behavior of trace elements during magmatic differentiation is a knowledge of the way in which elements distribute between fractionating phases and the variation in element partitioning with changes of temperature, pressure, and phase composition. A quantitative expression for the distribution of an element between two coexisting phases, A and B, is most conveniently represented by the Nernst partition coefficient, defined as the ratio of the element's concentration in respective phases (i.e., Di = Xixtl/xiliq ). During the last decade a number of experimental studies designed to characterize mineral-liquid element partitioning (for example, Watson [1977], Ryerson and Hess [1978], Hart and Davis [1978], Leeman [1978], Takahashi [1978], and Mysen and Virgo [1980], among others) have shown that one of the most important factors influencing the distribution of trace and minor elements between phenocrysts and silicate liquid is the bulk composition and hence structure of the melt phase. Although the actual magnitude of crystal-liquid partition coefficien...

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Section: Ion Microprobe Techniquesmentioning

confidence: 99%

Effects of silicate liquid composition on mineral‐liquid element partitioning from Soret diffusion studies

Lesher¹

1986

J. Geophys. Res.

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“…Metal atom clusters have also been observed in rf-spark sources [3] and in sputtering ion sources [4].…”

Section: Introductionmentioning

confidence: 99%

Ab initio Hartree–Fock and configuration‐interaction treatment of the interaction between two nickel atoms

Shim

Dahl

Johansen

1979

Int J of Quantum Chemistry

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AbstractsThe interaction between two nickel atoms in the configurations (3d)'(4s)* and (3d)9(4s)' has been calculated using ab initio methods (Hartree-Fock and configuration interaction). The results of the calculations compare favorably with the optical spectrum. The discrepancy between the calculated and the experimental dissociation energy is discussed, and a new estimate of the dissociation energy is given. The configuration-interaction calculations show that the interaction between the two nickel atoms is of a very complex nature. In spite of this the binding can be interpreted in a simple way. The bond is mainly due to the 4sug molecular orbital while the 3d orbitals of the two nuclei are exchange coupled. ' a Cte calculee par des methodes de type ab initio (Hartree-Fock et interaction de configurations). Les resultats sont en bon accord avec le spectre optique. La difference entre les energies de dissociation calculee et mesuree est discutke et on donne une nouvelle estimation de l'energie de dissociation. Les calculs CI montrent que I'interaction entre deux atomes de nickel est de nature tres complexe. Malgr6 cela la liaison peut &tre interpretee d'une faGon simple; elle est due principalement a I'orbitale molkculaire 4sug, tandis que les orbitales 3d des deux noyaux sont couplees par I'effet d'tchange. L'interaction entre deux atomes de nickel dans les configurations (3d)'(4s)* et (3d)'(4s) Die Wechselwirkung zwischen zwei Nickelatomen in den Konfigurationenist mittels ab-initio-Methoden (Hartree-Fock und Konfigurationswechselwirkung) berechnet worden. Die Ergebnisse der Berechnungstimmen mit dem optischen Spektrum gut iiberein. Der Unterschied zwischen der berechneten und der experimentellen Dissoziationsenergie wird diskutiert, und eine neue Abschatzung dieser Grosse wird gegeben. Die Konfigurationswechselwirkungsberechnungen zeigen, dass die Wechselwirkung zwischen zwei Nickelatomen sehr komplexer Natur ist. Trotzdem kann die Bindung in einer einfachen Weise interpretiert werden. Sie riihrt hauptsachlich von dem Molekiilorbital 4sug her, wahrend die 3d-Orbitale der zwei Kerne durch Austausch gekoppelt sind.

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“…These are called Magic Numbered Clusters. 28 For clusters intermediate in size between the magic numbers, the excess particles reside on the surface of a dense icosahedral cluster. Dense icosahedral clusters are solidlike at low temperatures because the atoms vibrate about a single minimum on the potential surface.…”

Section: Structuresmentioning

confidence: 99%

Thermodynamic properties and homogeneous nucleation rates for surface-melted physical clusters

McClurg

Flagan

Goddard

1996

The Journal of Chemical Physics

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We predict the free energy of van der Waals clusters (F n ) in the surface-melted temperature regime. These free energies are used to predict the bulk chemical potential, surface tension, Tolman length, and vapor pressure of noble gas crystals. Together, these estimates allow us to make definitive tests of the capillarity approximation in classical homogeneous nucleation theory. We find that the capillarity approximation underestimates the nucleation rate by thirty orders of magnitude for argon. The best available experiments are consistent with our calculation of nucleation rate as a function of temperature and pressure. We suggest experimental conditions appropriate for determining quantitative nucleation rates which would be invaluable in guiding further development of the theory. To make the predictions of F n , we develop the Shellwise Lattice Search ͑SLS͒ algorithm to identify isomer fragments and the Linear Group Contribution ͑LGC͒ method to estimate the energy of isomers composed of those fragments. Together, SLS/LGC approximates the distribution of isomers which contribute to the configurational partition function ͑for up to 147-atom clusters͒. Estimates of the remaining free energy contributions come from a previous paper in this series.

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Observation of clusters in a sputtering ion source

Cited by 96 publications

References 11 publications

Effects of silicate liquid composition on mineral‐liquid element partitioning from Soret diffusion studies

Effects of silicate liquid composition on mineral‐liquid element partitioning from Soret diffusion studies

Ab initio Hartree–Fock and configuration‐interaction treatment of the interaction between two nickel atoms

Thermodynamic properties and homogeneous nucleation rates for surface-melted physical clusters

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