Evidence for a size-dependent melting of sodium clusters

Martin, T. P.; Näher, U.; Schaber, H.; Zimmermann, Uwe

doi:10.1063/1.466530

Cited by 133 publications

(69 citation statements)

References 20 publications

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“…43 As can be seen from Fig. 1, special attention was paid to achieving a constant temperature profile FIG.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…A similar size dependence was already observed in the melting behavior of sodium clusters. 43 However, in each individual case the topology of the PES plays an important role and therefore the transition temperatures can locally fluctuate. For example, the barrier height between the different structural regions and the length of the transition path vary from cluster to cluster.…”

Section: A Decay Behavior Of Fullerene Dimersmentioning

confidence: 99%

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Structural transition in(C60)nclusters

et al. 2002

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The structure of (C 60 ) n clusters (nϭ1-150) was investigated by heating them to definite temperatures in a helium bath ͑heating cell͒ with subsequent characterization in a time-of-flight mass spectrometer. The intensity anomalies in the resulting mass spectra reflect particularly stable configurations that resisted evaporation. However, the set of enhanced peaks ͑magic numbers͒ turned out to be temperature dependent. Clusters heated to a moderate temperature of 490 K yielded mass spectra indicating the presence of icosahedral structures that can be characterized by a set of unusually strong peaks, namely nϭ13, 19, 23, 26, 35, 39, 43, 46, 49, 55, 55 ϩ3m, 116, 125, 131, 137, and 147 (mϭ1-14). Based on constant-temperature molecular dynamics simulations it could be concluded that these icosahedra represent metastable structures that had not yet attained thermal equilibrium on the experimental time scale (t s ϭ0.5 ms). Only when the (C 60 ) n clusters were heated to appreciably higher temperatures they could reach thermodynamical equilibrium, manifested by a thermally induced structural transition into close-packed structures, decahedral structures and structures based on the 98-Leary tetrahedron. Thus, mass spectra of clusters heated to 600 K demonstrate the new set of magic numbers, nϭ38, 48, 58, 61, 64, 68, 71, 75, 77, 84, 89, 91, 96, and 98. Additionally, the experimental arrangement used allows both charged and neutral (C 60 ) n clusters to be studied. Thereby, it was possible to show that the structure of large (C 60 ) n clusters is insensitive to their charge state (Ϫ/n/ϩ), disproving a hypothesis that has been discussed in the literature for several years. The heating cell was also used to study the thermally induced dissociation in the fullerene dimers (C 60 ) 2 , (C 70 ) 2 , and (C 60 ) 2 ϩ . The dissociation energies were determined to be 0.275 eV, 0.313 eV, and 0.37 eV, respectively (Ϯ0.08 eV).

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“…43 As can be seen from Fig. 1, special attention was paid to achieving a constant temperature profile FIG.…”

Section: Experimental Methodsmentioning

confidence: 99%

Section: A Decay Behavior Of Fullerene Dimersmentioning

confidence: 99%

Structural transition in(C60)nclusters

et al. 2002

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“…[5][6][7][11][12][13] Experimental evidence of the decrease in T m has been demonstrated by a variety of techniques. 2,[14][15][16][17][18] In addition, the influence of surrounding matrix on T m has been demonstrated, e.g., in our previous work. 19 However, the influence of the interaction between the metal nanoparticles ͑or filling factor of nanocomposite͒ on their melting point is an unstudied problem.…”

Section: Introductionmentioning

confidence: 99%

Influence of interparticle interaction on melting of gold nanoparticles in Au/polytetrafluoroethylene nanocomposites

Yeshchenko

Dmitruk

Grytsenko

et al. 2009

Journal of Applied Physics

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The temperature dependence of the surface plasmon resonance energy and width in 5 nm spherical gold nanoparticles embedded in a polymer polytetrafluoroethylene matrix has been studied using absorption spectroscopy. The jumplike features have been observed in these dependences indicating the melting of gold nanoparticles at temperatures considerably lower than the bulk melting point. The interaction between gold nanoparticles sufficiently affects the melting of nanoparticles. The increase in the filling factor of the particles leads to a decrease in the melting temperature of gold nanoparticles.

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“…The heating cell is a further development of the heating nozzle used for the study of size-dependent melting of sodium clusters. 14 The new design was inspired by similar cells used by other experimentalists. 6,9,15,16 The main part is a 120 mm long copper tube ͑1͒ of 6 mm inner diameter, which is attached directly to the exit nozzle of the cluster source ͑2͒.…”

Section: Methodsmentioning

confidence: 99%

A combined heating cooling stage for cluster thermalization in the gas phase

Ievlev

Küster

Enders

et al. 2003

Review of Scientific Instruments

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We report on the design and performance of a combined heating/cooling stage for the thermalization of clusters in a gas phase time-of-flight mass spectrometer. With this setup the cluster temperature can sensitively be adjusted within the range from 100 up to 800 K and higher. The unique combination of a heating stage with a subsequent cooling stage allows us to perform thermodynamic investigations on clusters at very high temperatures without quality losses in the spectra due to delayed fragmentation in the drift tube of the mass spectrometer. The performance of the setup is demonstrated by the example of (C 60 ) n clusters.

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Evidence for a size-dependent melting of sodium clusters

Cited by 133 publications

References 20 publications

Structural transition in(C60)nclusters

Structural transition in(C60)nclusters

Influence of interparticle interaction on melting of gold nanoparticles in Au/polytetrafluoroethylene nanocomposites

A combined heating cooling stage for cluster thermalization in the gas phase

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