Evaporation of atoms from metal clusters

Bertsch, G. F.; Oberhofer, Nadia; Stringari, S.

doi:10.1007/bf01543953

Cited by 35 publications

(25 citation statements)

References 5 publications

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“…Here, ev is the bulk specific internal energy and is given by (2). The specific entropy can be also written as the sum of a volume part and a surface part as:…”

Section: = (~_ T Dc~'~ Amentioning

confidence: 99%

“…The relation between T and e is given by (2). If surface effects are neglected (bulk approximation) the quantities Dec and s(e) used in (3) are given by:…”

Section: _ G M O E-~dn P N -I ( E --E --Dn) A(e)ede (3) Zw(e = Ne) Hmentioning

confidence: 99%

“…absorption of one photon) remains in a solid state and pN(E) can be derived from standard harmonic models as the Debye model for instance. In using this harmonic level density, the Weisskopf model can then be used to estimate evaporation rates [3,2]. At higher excitation energy, the excited cluster behaves more like a hot liquid droplet than a solid and the harmonic approximation is no longer valid to describe the internal behavior of the cluster.…”

Section: Introductionmentioning

confidence: 99%

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Evaporation of hot mesoscopic atomic metal clusters

Hervieux

Gross

1995

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The evaporation times of hot mesoscopic sodium clusters are estimated using the microscopic and microcanonical statistical model of Weisskopf and the macroscopic canonical kinetic gas theory. The level density of liquid sodium clusters as function of the internal excitation energy is computed from the experimentally known thermodynamic quantities of the bulk matter. In using the known temperature dependent surface tension and standard thermodynamics, both theories are corrected to take into account finite size effects. By this method it is possible to obtain decay rates and internal level densities of mesoscopic clusters at excitations where any harmonic approximation breaks down. For clusters having more than about 200 atoms, the evaporation times obtained from the two models are practically equal.

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“…Here, ev is the bulk specific internal energy and is given by (2). The specific entropy can be also written as the sum of a volume part and a surface part as:…”

Section: = (~_ T Dc~'~ Amentioning

confidence: 99%

“…The relation between T and e is given by (2). If surface effects are neglected (bulk approximation) the quantities Dec and s(e) used in (3) are given by:…”

Section: _ G M O E-~dn P N -I ( E --E --Dn) A(e)ede (3) Zw(e = Ne) Hmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaporation of hot mesoscopic atomic metal clusters

Hervieux

Gross

1995

Z Phys D - Atoms, Molecules and Clusters

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“…The condition '(7) for the saddle point may be rewritten as the familiar implicit relation equating energy = E(T, N), the cluster energy with the average (10) which determines the temperature. The integral is calculated expanding the exponent of the integrand up to second order in fi -fl', where the coefficient of the second order terms can be expressed in terms of the heat capacity…”

Section: E ( T N ) = F ( T N ) + T S ( T N )mentioning

confidence: 99%

“…Combined with different expressions for the level densities, it has been used in refs. [5,[8][9][10]] to derive evaporation rates of neutral atoms from clusters. The probability per unit time to evaporate an atom with the kinetic energy e from a cluster with mass number N and energy E is [6] ma p ( E -e , N -1) d&…”

Section: General Expressionmentioning

confidence: 99%

Evaporation rates for liquid clusters

Frauendorf

1995

Z Phys D - Atoms, Molecules and Clusters

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Abstract. An expressxon for the evaporation rate of neutral atoms from a hot liquid cluster is suggested. It combines Weisskopf's statistical model with a level density that is derived from the experimentally known free energy of a macroscopic droplet of the cluster material. For the case of sodium clusters, it is compared with the rate based on the level density of a system of oscillators. For the same internal energy the latter gives substantially larger evaporation rates, whereas for equal temperature the increase is moderate. For large clusters the electronic contribution to the entropy can no longer be neglected.

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On the decay of hot metallic clusters by evaporation

Fröbrich

1997

Annalen der Physik

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Starting from the Weisskopf theory decay rates for the evaporation of cluster atoms from hot liquid alkali metal clusters are derived. The crucial input quantity is the level density which is determined from empirical properties of the bulk, namely from the specific heat and the thermal expansion coefficient. The resulting rate expression is compared with decay rate formulas given by Engelking, Klots and Gspann. Furthermore, critical (appearance) sizes of multiply charged clusters are calculated by equating the rates for neutral monomer and light charged particle emission. Also shrinking and cooling rates of large hot clusters are determined by treating multiple emission of cluster atoms, thus establishing a time scale for the decay of clusters theoretically.

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Evaporation of atoms from metal clusters

Cited by 35 publications

References 5 publications

Evaporation of hot mesoscopic atomic metal clusters

Evaporation of hot mesoscopic atomic metal clusters

Evaporation rates for liquid clusters

On the decay of hot metallic clusters by evaporation

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