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Buck, U.; Krohne, R.

doi:10.1103/physrevlett.73.947

Cited by 47 publications

(28 citation statements)

References 20 publications

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“…From the results shown in Fig. 2, we assume that gold atoms have migrated over a distacne d ∼ 5 nm (which is half the average diameter of a-Sb clusters) in an a-Sb cluster in less than 1 s at 250 K. When values of d ∼ 5 nm and a ∼ 0.25 nm are employed, a value of 4×10 2 is obtained for n. In general, the number of jumps n can be expressed as n = ν exp(−E/kT ), where ν is the Debye frequency, E the activation energy, k the Boltzmann constant, and T the temperature [12]. Employing values of T ∼ 250 K and ν ∼ 10 13 , a value of ∼ 0.5 eV is obtained for the activation energy E. This value gives a guide for the upper limit of the activation energy of gold diffusion in a-Sb clusters, since the Debye frequency ν in clusters is expected to be lower than that in the corresponding bulk materials [13].…”

Section: Discussionmentioning

confidence: 99%

Spontaneous alloying of gold clusters into nanometer-sized antimony clusters

Yasuda

Mori

1997

Z Phys D - Atoms, Molecules and Clusters

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Alloying behavior of gold into nm-sized amorphous antimony (a-Sb) clusters has been studied by transmission electron microscopy (TEM), employing gold clusters in contact with a-Sb clusters. In order to produce gold clusters on individual a-Sb clusters, a-Sb clusters on an amorphous carbon film were cooled down to 96 K, and gold was then condenced on the film. When gold clusters in contact with a-Sb clusters are gradually heated from 96 to 290 K, dissolution of gold into a-Sb clusters sets in around 200 K and clusters of a-(Sb-Au) alloys are produced. With increasing annealing temperture, more gold is absorbed into individual a-Sb clusters, and when the gold concentration in a-(Sb-Au) clusters reaches to the stoichiometric composition of AuSb 2 , these amorphous clusters crystallize into AuSb 2 clusters. The crystallization temperature decreases with decreasing size of initial a-Sb clusters.

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Section: Discussionmentioning

confidence: 99%

Spontaneous alloying of gold clusters into nanometer-sized antimony clusters

Yasuda

Mori

1997

Z Phys D - Atoms, Molecules and Clusters

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“…Typical examples are the study of the vibrational energy transfer [4], the fusion between clusters [5], the formation of endohedral complexes [6], and the collision induced dissociation (CID) [7]. There is also a lasting interest to study non-adiabatic cluster collisions where electronic transitions occur.…”

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confidence: 99%

Excitation and Relaxation in Atom-Cluster Collisions

Saalmann

Schmidt

1998

Phys. Rev. Lett.

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Electronic and vibrational degrees of freedom in atom-cluster collisions are treated simultaneously and self-consistently by combining time-dependent density functional theory with classical molecular dynamics. The gradual change of the excitation mechanisms (electronic and vibrational) as well as the related relaxation phenomena (phase transitions and fragmentation) are studied in a common framework as a function of the impact energy (eV. . . MeV). Cluster "transparency" characterized by practically undisturbed atom-cluster penetration is predicted to be an important reaction mechanism within a particular window of impact energies.PACS numbers: 31.70. Hq, 31.15.Ew, 34.50.Bw, 36.40.Ei Collisions with atomic clusters represent a relatively new branch of collision physics as compared to the well established fields of ion-atom collisions [1] and ion-solid interaction [2]. The study of cluster collisions is of particular interest and importance because it offers the possibility to tackle bridge-building questions (like the continuous transition from individual excitations in the elementary ion-atom collision to the macroscopic stopping power in solids) as well as fundamental problems (like phase transitions in finite systems). It is also an extremely challenging and complicated field as the comprehensive understanding of these collisions still requires the development of basically new techniques for both, large-scale (multi-parametric) experiment and manybody (quantum-mechanical) theory. In this request, the present situation resembles very much that of nuclear physics at the beginning of the 80's [3].Experimentally, large progress has been made, meanwhile, in the investigation of adiabatic cluster collisions where the reaction mechanism is determined by vibrational excitations only. Typical examples are the study of the vibrational energy transfer [4], the fusion between clusters [5], the formation of endohedral complexes [6], and the collision induced dissociation (CID) [7]. There is also a lasting interest to study non-adiabatic cluster collisions where electronic transitions occur. Experiments in this field concern the measurements of the charge transfer [8][9][10], ionization and electronic excitation [11], as well as the selective observation of vibrational and electronic excitations [12].Theoretically, adiabatic cluster collisions can be well described by quantum molecular dynamics (QMD) or molecular dynamics (MD) [13][14][15][16][17]. Also, isomeric [18] and solid-liquid phase transitions [19,20] [25,26] approaches where the atomic structure, and thus the vibrational degrees of freedom, are not taken into account. Recently, a general theory has been developed [27] which is able to describe simultaneously adiabatic and non-adiabatic collisions and, in particular, also the still completely unknown transition regime where both -electronic and vibrational -excitations occur. This so-called non-adiabatic quantum molecular dynamics (NA-QMD) [27] can also be used to study, for the first time, phase transitions i...

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“…of the atomic radii) proceeds at a cycle of about 3 ps (see middle panel of figure 2), corresponding to a volume frequency of about 1.4 meV. This is within fac- tor two the surface vibration frequency observed in neutral Ar clusters of that size [57], which is quite gratifying in view of the structural differences (Na cluster embedded, high net charge) between these two systems. A detailed comparison will have to be worked out in future studies.…”

Section: Detailed View At the Propagation Of Ions And Atomsmentioning

confidence: 69%

Embedded metal cluster in strong laser fields

Fehrer

Dinh

Reinhard

et al. 2008

Computational Materials Science

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We discuss microscopic mechanisms of the violent dynamics following strong laser excitation of a metal cluster embedded in a rare gas matrix, taking as test case Na8@Ar434. This covers at least two aspects: first, it represents the typical experimental situation of metal clusters handled in raregas matrices or a finite drop of surrounding raregas material, and second, it serves as a generic test case for highly excited chromophores in inert surroundings addressing questions of energy transport and perturbation of the medium. We simulate the process up to 10 ps using a mixed quantum mechanical (for the electrons) and classical (ions and atoms) approach and analyze the emerging dynamics with respect to all basic constituents: cluster electrons, cluster ions, and matrix atoms. We find several stages of relaxation taking place with time scales from a few fs to over a few ps and much slower processes remaining for long after the simulation. A particularly interesting aspect is that the surrounding raregas material stabilizes a highly charged metal cluster which would otherwise explode without delay.

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Surface Vibrations from Small Clusters to the Solid: He Atom Scattering fromArn

Cited by 47 publications

References 20 publications

Spontaneous alloying of gold clusters into nanometer-sized antimony clusters

Spontaneous alloying of gold clusters into nanometer-sized antimony clusters

Excitation and Relaxation in Atom-Cluster Collisions

Embedded metal cluster in strong laser fields

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