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  • 36.40. +d  (35)
  • Springer  (35)
  • 1990-1994  (35)
  • 1970-1974
  • 1950-1954
  • 1991  (35)
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  • Springer  (35)
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  • 1990-1994  (35)
  • 1970-1974
  • 1950-1954
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  • 1
    Electronic Resource
    Electronic Resource
    Electronic shells and shells of atoms in metallic clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 25-29 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 82.80Ms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Intensity anomalies (magic numbers) have been observed in the mass spectra of sodium clusters containing up to 22 000 atoms. For small clusters (Na n ,n≤1500) the anomalies appear to be due to the filling of electronic shells (groups of subshells having the same energy). The shells can be characterized rather well by a pseudoquantum-number, indicating the possible existence of a symmetry higher than spherical. The mass spectra of larger clusters (1500≤n≤22 000) are well explained by the completion of icosahedral or cuboctahedral shells of atoms. The fact that the two types of shells (electron and atom) occur in distinct and non-overlapping size intervals might indicate the existence of a “liquid” to “solid” transition in going from small to large clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448248
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  • 2
    Electronic Resource
    Electronic Resource
    Electronic structure of selenium- and tellurium-clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 233-235 
    Details
    ISSN: 1434-6079
    Keywords: 33.60.Cv ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The vacuum-UV-photoelectron spectra (hν=10.0 eV or 8.3 eV) of selenium- and tellurium-clusters of different sizes (up to Se25 and Te8) were measured in a molecular beam by a photoion-photoelectron-coincidence experiment. Especially, the photoelectron spectra (4p-π-electrons) of the selenium-clusters converge with growing cluster size to the well known spectra of amorphous solid selenium by taking into account the dielectric constant of the bulk material. The experimental results indicate the first evidence that larger selenium aggregates are van der Waals clusters of the molecules Se5, Se6, Se7 and Se8 which are contained in the equilibrium vapour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448300
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison between selenium and tellurium clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 237-239 
    Details
    ISSN: 1434-6079
    Keywords: 35.20.Vf ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Selenium and tellurium clusters are produced by the inert gas condensation technique. The mass spectra of both species are completely different and reveal different properties. In selenium, a periodicity of 6–7 is observed and may be interpreted by the binding energy between small cyclic molecules. Moreover, it was very difficult to obtained large clusters probably because the binding energy between these molecules is very small. In tellurium, these periodic structures do not exist and large clusters are easily obtained in nucleation conditions where only small selenium clusters are present. These results are discussed and a simple nucleation model is used to illustrate this different behavior. Finally these clusters properties are correlated to the bulk structure of both materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448301
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetic properties of free alkali and transition metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 241-245 
    Details
    ISSN: 1434-6079
    Keywords: 75.50.Bb ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Stern-Gerlach deflections of small alkali clusters (N〈6) and iron clusters (10〈N〈500) show that the paramagnetic alkali clusters always have a non-deflecting component, while the iron clusters always deflect in the high field direction. Both of these effects appear to be related to spin relaxation however in the case of alkali clusters it is shown that they are in fact caused by avoided level crossing in the Zeeman diagram. For alkali clusters the relatively weak couplings cause reduced magnetic moments where levels cross. For iron clusters however the total spin is strongly coupled to the molecular framework. Consequently this coupling is responsible for avoided level crossings which ultimately cause the total energy of the cluster to decrease with increasing magnetic field so that the iron clusters will deflect in one direction when introduced in an inhomogeneous magnetic field. Experiment and theory are discussed for both cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448302
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  • 5
    Electronic Resource
    Electronic Resource
    Metallic susceptibility in giant molecule: Pd561Phen36O200 (1991)
    Springer
    The European physical journal 19 (1991), S. 267-270 
    Details
    ISSN: 1434-6079
    Keywords: 75.20.−g ; 35.20.My ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The giant metal cluster molecule Pd561Phen36O x is the largest member of a series that has recently been prepared by Schmid [1]. Pronounced size effects are expected to show up in the magnetic properties of metal particles of the size of the Pd-561 core of the molecule. We have measured the susceptibility on four different batches of the material, with quite satisfactory reproducibility. There is a low temperature tail that is attributed to small amounts of impurities. The nearly temperature-independent paramagnetism that is observed is most probably due to an exchange enhanced Pauli spin susceptibility and is already close to the bulk value. The absence of size effects, i.e. a drop at low temperatures, is either due to interactions between the clusters or a result of a very small energy level spacing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448308
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  • 6
    Electronic Resource
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    Electronic properties of divalent-metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 165-167 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transition from van der Waals to metallic bonding expected to occur in divalent-metal clusters (e.g., Be n , Mg n , Hg n ) as a function of cluster size is discussed. Theoretical results for several electronic properties reflecting this transition in Hg n -clusters are briefly reviewed and compared with available experiments. The limitations of the present theory particularly concerning the role of correlations and van der Waals interactions are discussed and possible improvements are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448282
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  • 7
    Electronic Resource
    Electronic Resource
    Semiclassical variational calculation of liquid-drop model coefficients for metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 101-103 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 31.20.Lr ; 31.20.Sy ; 03.65.Sq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on semiclassical density variational calculations for spherical alkali metal clusters in the jellium model. We derive liquid-drop model expansions for total energy, ionisation potential and electron affinity and test the coefficients numerically for clusters with up toN=105 atoms. From the limitN→∞, we obtain excellent agreement with surface tensions and work functions evaluated for an infinite plane metal surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448265
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  • 8
    Electronic Resource
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    Ultraviolet photoelectron studies of the molecules Se5, Se6, Se7 and Se8 with relevance to their geometrical structure (1991)
    Springer
    The European physical journal 19 (1991), S. 229-231 
    Details
    ISSN: 1434-6079
    Keywords: 31.20. +Z ; 33.60.Cv ; 35.20.Vf ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The vacuum-UV-photoelectron spectra (hν=10.0 eV) of Se2, Se5, Se6, Se7 and Se8 were measured. The isolated particles were examined in a supersonic molecular beam employing the photoelectron-photocation-coincidence technique. The structures of the photoelectron spectra of selenium molecules with even and odd numbers of atoms differ in a characteristic manner. Whereas the spectra of Se6 and Se8 show one single broad band, three separated bands with different intensities are observed for Se5 and two for Se7. An attempt to connect these experimental observations with the geometrical structure of the molecules shows that the photoelectron spectra are consistent with theC 1h -symmetry of the Se5 and Se7 rings proposed in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448299
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  • 9
    Electronic Resource
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    Simple metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 1-6 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 35.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The response of alkali cluster ions to an optical excitation is investigated for two different photon energy domains. Below the ionization potential giant resonances in the photoabsorption cross-section are observed for closed shell species. Above the ionization potential, the ionization process competes with the photofragmentation process. The number of valence electrons determines both the behavior of the photoabsorption spectrum and the evolution of the ionization cross-section with the cluster size. The stability of the clusters against an excess of charge is examined through the observation of an asymmetric fission of Na n ++ . Experimental results are discussed in term of an electrostatic model giving an estimate of the critical size of stability and of the height of the coulombic barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448244
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  • 10
    Electronic Resource
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    Optical spectra of sodium microclusters (1991)
    Springer
    The European physical journal 19 (1991), S. 43-45 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 33.20.Kf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Photoabsorption spectra have been measured for free neutral sodium clusters containing fromN=3 to 40 atoms. In the size range ofN≈3 to 5, a transition occurs from molecule-like absorption to collective excitations of the valence electrons. ForN≈6 to 12, the data are well described by an ellipsoidal shell model. In open-shell clusters, the multiple surface plasma resonances expected for spheroidal or ellipsoidal shapes are observed. The experimental resonance positions provide a sensitive measurement of the cluster distortions. ForN≳13, the per atom strength of these collective resonances is reduced; this may be due to peak fragmentation caused by interaction between the surface plasmon and nearby single-electron resonances. In three distinct wavelength regions, one of which corresponds to the position of the Na atom “D-lines”, additional absorption is seen in the spectra of all investigated clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448251
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  • 11
    Electronic Resource
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    Thermal electronic properties of alkali clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 51-53 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 31.20.Sy ; 05.30.−d ; 65.60. +m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We apply the finite-temperature Kohn-Sham method to alkali metal clusters, using the spherical jellium model and treating the valence electrons as a canonical system in the heat bath of the ions. We study the shell effects in the total free energyF(N) and the entropyS(N) for neutral clusters containingN atoms. Their strongest temperature dependence is due to the finite ground-state valueS 0〉0 of the electronic entropy for non-magic clusters. It leads to a decreasing amplitude and an increasing smear-out of the saw-tooth structure in the first difference Δ1 F(N)=F(N−1)−F(N) with increasing temperatureT and cluster sizeN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448253
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  • 12
    Electronic Resource
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    Applying ZEKE-spectroscopy to clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 59-61 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 33.60. −q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper we describe the application of a special form of electron photodetachment spectroscopy, zero electron kinetic energy (ZEKE) spectroscopy, to the study of cold metal cluster anions. From this study we have obtained vibrational and thus structural information of several neutral and charged clusters, e.g. Au 2 −/0 , Ag 3 −/0 , Sn 2 −/0 and Al 3 −/0 . In addition, in separate measurements of the relative photodetachment cross section of Au 2 − , we have discovered sharp resonances which are due to electronic autodetachment from a short lived excited state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448255
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  • 13
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    A pseudo-Jahn-Teller treatment of the B system of Na3 (1991)
    Springer
    The European physical journal 19 (1991), S. 63-66 
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    ISSN: 1434-6079
    Keywords: 33.10 Lb ; 33.70. −w ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract TheB system of the two-photon ionization spectrum of Na3 often is quoted as an example of fractional quantization of the pseudorotational motion. In the present paper we investigate the influence of a nearby electronic state on the nuclear motion. It turns out that the experimental results may be understood equally well in a picture which implies integer instead of fractional quantization of the pseudorotation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448256
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  • 14
    Electronic Resource
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    Photoabsorption spectra of Cs n O and Cs n clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 81-84 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 33.20 Ea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Photoabsorption spectra of several Cs N+2O and Cs N clusters were obtained by means of laser-induced beam-depletion techniques. The strong absorption of clusters withN≥3 in the near infrared indicates that collective motion might play an important role. Dipole transitions between molecular orbitals, enhanced by plasmon oscillations, generate remarkably distinct spectra for(a) closed-shell clusters atN=8 and(b) geometrically symmetric clusters like Cs6O and Cs14O.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448260
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  • 15
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    The response of metal clusters toq- andL-dependent external fields (1991)
    Springer
    The European physical journal 19 (1991), S. 89-91 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 31.20.Sy ; 71.45.Gm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have calculated the static polarizability and mean excitation energy of metal clusters submitted toq-andL-dependent external fields ofj L (qr)Y L0(Ω) type. Use has been made of an Extended Random-Phase Approximation which includes exchange and correlation effects within a local model, and of the spherical jellium model to describe the neutralizing positive background.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448262
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  • 16
    Electronic Resource
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    Surface and volume collective modes in small clusters and their interaction with single-particle levels (1991)
    Springer
    The European physical journal 19 (1991), S. 105-107 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 72.45. −d ; 31.20.Lr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract As has been recently established, collective excitations in small metal clusters exhibit some unusual features. A theoretical analysis of cluster photoabsorption spectra is presented. It is shown that small systems can support volume collective modes which, unlike in the case of bulk metals, make a noticeable contribution to photoabsorption. Furthermore, single particle-hole transitions cause splitting of resonance peaks. The theory agrees well with experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448266
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  • 17
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    The self-consistent spheroidal jellium model of open-shell monovalent metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 109-111 
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    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Recently, we have proposed a microscopic model, describing the properties of open-shell, Jahn-Teller deformed monovalent-metal clusters [1]. The model is based on the self-consistent ground-state calculation, allowing the spheroidal (axial) deformation of the ionic jellium background, driven by the open-shell valence electron structure. The ground state electronic properties of such clusters are further investigated and compared to recent experimental data: ionization potentials, electron affinities and binding energies of neutral monomers to cationic clusters [2].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448267
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  • 18
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    Calculated electronic properties of medium sized sodium clusters: the inhomogeneous jellium model (1991)
    Springer
    The European physical journal 19 (1991), S. 113-115 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 31.20.Sy ; 71.25.M
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Recently observed magic number data for Na N clusters in the size range from 100 to 900 atoms cannot be fully explained by density functional calculations using a homogeneous, spherical positive charge background. However, a centrally compressed spherical background yields steps in the ionization potential at just those magic numbers observed experimentally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448268
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  • 19
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    Investigation of large electronic shells in Cs-compound clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 117-119 
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    ISSN: 1434-6079
    Keywords: 71.50. +t ; 31.20.Sy ; 36.40. +d ; 82.80.Ms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Magic numbers in cluster mass spectra can be caused by either geometric or electronic structure. The study of metallic compound clusters allows the number of atoms and the number of electrons in clusters to be controlled independently. We report magic numbers in the mass spectra of Cs-compound clusters containing up to 700 free electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448269
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  • 20
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    Multipotential model for atoms in alkali microclusters (1991)
    Springer
    The European physical journal 19 (1991), S. 121-124 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 21.60.Cs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An alkali-atom shell model for alkali microclusters is introduced, where the quantum constituent is the neutral atom itself considered as a heavy fermion in a central potential created by all atoms in each shell of the cluster. Thus, here the magic numbers are due to atoms and not to electrons as in jellium models. The model is applicable under conditions (of production, temperature, size, etc.) not favoring delocalization of valence electrons. For conditions favoring electron delocalization the jellium model is applicable. New experiments are suggested via nuclear methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448270
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  • 21
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    Small clusters made up of three kinds of neutral alkali atoms (1991)
    Springer
    The European physical journal 19 (1991), S. 125-127 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 21.80. +a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Small clusters made up of three kinds of neutral alkali atoms, i.e. clusters of the form X ℓ Y m Z n , are theoretically studied. These clusters exhibit three series of magic numbers, one for each kind of atoms. That is,ℓ,m, andn independently can be magic numbers rather than their cumulative numberℓ+m+n or, in other words, magic numbers in alkali clusters composed of neutral atoms are due to atoms rather than to delocalized electrons as in jellium model. Of course, if conditions favor delocalization of electrons,ℓ+m+n can be magic but then we have no neutral atoms which are prerequisite for an application of the present model.
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    URL: http://dx.doi.org/10.1007/BF01448271
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  • 22
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    Electronic properties of aluminum clusters compared with the jellium model (1991)
    Springer
    The European physical journal 19 (1991), S. 133-135 
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    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The experimental polarizabilities, ionization potentials and electron affinities of aluminum clusters are compared with jellium predictions. It is found that the clusters have radii and work functions which are close to the jellium model predictions for clusters with more than 13 atoms. The polarizabilities of Al n correspond with the jellium only forn〉40 and the shell structure features in the ionization potentials are anomalous up to 37. We conclude that nonjellium effects are important up ton=40.
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    URL: http://dx.doi.org/10.1007/BF01448273
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  • 23
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    Stability of isomeric Na n clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 141-143 
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    ISSN: 1434-6079
    Keywords: 31.20.Sy ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method which combines density functional theory and the use of pseudopotentials is applied to obtain ground state and low-lying metastable geometries of Na n clusters (7≤n≤40). The large variation in the magnitude of energy gaps between isomers suggests that the melting temperature is not a simple monotonous function of size. A detailed study of the differences between electronically stabilized (n=8, 20, 40) and structurally stabilized (n=13) clusters suggests some clues to understand the intriguing behaviour of Na13.
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    URL: http://dx.doi.org/10.1007/BF01448275
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  • 24
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    Shell effects on fragmentations of doubly-charged silver clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 149-150 
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    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Shell effects are found in the size distributions of fission fragments from doubly-charged silver clusters. The energy differences between parent cluster and sum of a pair of fragmented clusters are calculated for various fission channels using the theory of shell corrections. Oscillative structures observed in the size distribution are shown to be due to shell effects of fragments. It is also found that the cluster deformation due to shell effects produces the even-odd alternation in the size distribution.
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    URL: http://dx.doi.org/10.1007/BF01448277
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  • 25
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    Shell effects on symmetric fragmentations of alkali-metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 145-147 
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    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Symmetric fragmentation of multiply charged alkali-metal clusters consisting of several tens of atoms is studied. The energy variation during the fragmentation process is calculated using the theory ofshell corrections, in which total energy is written as a sum of the liquid-droplet and shell correction terms. It is found that the variation of the shell correction term is much larger than that of the liquid-droplet one if the parent cluster is metastable. Fragmentation into nearly-magic cluster is most favored regardless of parent size since the barrier height for fragmentation is mainly determined by the shell configuration of fragments rather than that of the parent.
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    URL: http://dx.doi.org/10.1007/BF01448276
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  • 26
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    Electronic shell structure in multiply charged silver clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 151-152 
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    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Silver clusters are generated by standard laser vaporization technique and ionized via multiphoton ionization. Time-of-flight mass spectrometry reveals singly, doubly and triply charged clusters, Ag n z+ (z=1,2,3). The spectra show, for all charge states, intensity variations, indicating enhanced stabilities for cluster sizes with closed electronic configurations in accord with the spherical jellium model.
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    URL: http://dx.doi.org/10.1007/BF01448278
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  • 27
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    Photoelectron spectroscopy and UV/Vis-photoabsorption spectroscopy of isolated clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 161-164 
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    ISSN: 1434-6079
    Keywords: 33.60.Cv ; 35.20.Vf ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental innovations have allowed for the application of rather conventional spectroscopic molecular beam techniques to the study of electronic properties of molecular beam isolated neutral aggregates. Recent results for mercury clusters obtained by photoelectron spectroscopy and photoabsorption spectroscopy will be discussed. The experimentally available data for mercury clusters indicate a size dependent gradual evolution of metallic bulk properties in the approximate size region between 13 and 70 atoms.
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    URL: http://dx.doi.org/10.1007/BF01448281
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  • 28
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    Optical spectroscopy on size selected gold clusters deposited in rare gas matrices (1991)
    Springer
    The European physical journal 19 (1991), S. 157-159 
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    ISSN: 1434-6079
    Keywords: 29.25.Cy ; 36.40. +d ; 78.40. −q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on the successful “soft-landing” of size selected Au trimers in solid Krypton matrices. The Au cations are produced by sputtering, mass-selected in a quadrupole mass spectrometer, co-deposited with Krypton on a cooled CaF2 substrate, and neutralized by low energy electrons. The deposition of low kinetic energy cations (10 eV) gives rise to strong excitation bands, detected by the emitted fluorescence light, which are unambiguously attributed to Au trimers. The deposition and fragmentation process is qualitatively discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448280
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    Bonding properties of IIA and IIB dimers in density functional theory with gradient corrections to the local density approximation (1991)
    Springer
    The European physical journal 19 (1991), S. 169-171 
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    ISSN: 1434-6079
    Keywords: 31.20. −d ; 31.20.Sy ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have computed bonding properties of the IIA and IIB homonuclear dimers within the Pseudopotential — Density Functional scheme, including Gradient Corrections to the Local Density Approximation (LDA). Our computations confirm that Gradient Corrections offer a significant improvement over LDA for what concerns ground state properties of finite systems: The LDA error on bond energies is reduced by more than 50%. Although less impressive, the relative improvement on equilibrium distances and vibrational frequencies is also systematic and important. We briefly discuss the relevance of our results to the description of the non-metal to metal transition expected in clusters of these elements as a function of size.
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    URL: http://dx.doi.org/10.1007/BF01448283
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  • 30
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    Structural and dynamical properties of magnesium microclusters (1991)
    Springer
    The European physical journal 19 (1991), S. 173-176 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 31.20.Sy ; 61.50.Cj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present systematic Density Functional Theory-Local Density Approximation computations for neutral Magnesium clusters Mg n withn≤13. For the smaller sizes the ground state structure is optimized starting from selected symmetries and allowing for relaxation, Jahn-Teller distorsion and spin polarization. For the larger sizes we perform a simulated annealing based on the ab-initio Molecular Dynamics. By the same method, we study the thermal and dynamical properties of Mg10 and Mg16. The general picture emerging from these computations shows that already atn ≈10 these clusters have acquired many characteristic features of metallic Magnesium.
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    URL: http://dx.doi.org/10.1007/BF01448284
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  • 31
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    Structure of small rare earth clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 191-193 
    Details
    ISSN: 1434-6079
    Keywords: 35.20.Vf ; 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Rare earth clusters are produced by the inert gas condensation technique. The observed size distribution shows large peaks atn=13, 19, 23, 26, 29, 32, 34, 37, 39, 45, ... The beginning of this sequence (up to 34) has been already observed in argon clusters and recently by our group in barium clusters; this sequence may be interpreted in terms of icosahedral structures corresponding to the addition of caps on a core icosahedron of 13 atoms.
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    URL: http://dx.doi.org/10.1007/BF01448289
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  • 32
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    Generation of rare earth metal clusters by means of the gas-aggregation technique (1991)
    Springer
    The European physical journal 19 (1991), S. 195-197 
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    ISSN: 1434-6079
    Keywords: 36.40. +d ; 35.20 Wg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Generation of rare-earth clusters is achieved using a gas aggregation technique. Varying the nucleation conditions induces a change in the relative cluster abundances. This can be understood in terms of competing cubic versus icosahedron structures.
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    URL: http://dx.doi.org/10.1007/BF01448290
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  • 33
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    Photoabsorption spectra ofs 1-electron metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 13-17 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 33.80.Gj ; 33.20Kf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Collinear laser/molecular beam photodepletion spectroscopy has developed into a powerful tool for the determination of electronic absorption in neutral alkali metal clusters free of perturbing matrix effects. We briefly discuss the method, present data on selected Na x and Li y Na x−y ,x≤20, contrast measurements with the known optical response of larger colloidal metal clusters, compare microcluster spectra with the predictions of various models and speculate on future experimental and theoretical developments in this field.
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    URL: http://dx.doi.org/10.1007/BF01448246
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  • 34
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    Silver-halogen cluster compounds Ag n X m (n≥2; 0≤m≤n;X=F, Br) (1991)
    Springer
    The European physical journal 19 (1991), S. 401-404 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonstoichiometric silver-halogen cluster compounds Ag n X m (0≤m≤n;X=F, Br) are generated by cocondensation of Ag atoms and AgX species using a slightly modified gas aggregation technique. The AgX molecules are produced by partial decomposition of SF6 and Br2 respectively at the surface of the hot silver containing crucible, followed by the reaction of halogen atoms with silver, giving rise to the formation of AgX molecules. In a heterogeneous nucleation between these molecules and evaporated Ag atoms the afore mentioned cluster compounds are formed. The degree of halogenation can either be controlled by the adjustment of the silver evaporation rate, or even more easily by controlling the partial pressure of the halogenating agent. The mass spectra of singly charged halogenated clusters, which are generated by electron impact ionization, reflect the stability of ions. These mass spectra demonstrate that there is an alternation in the intensity pattern up to a relatively high degree of halogenation (m) for each of the investigated compound series Ag n X m ,n≤8. This behavior is similar to the well-known odd-even effect for pure metal clusters, allowing us to postulate the existence of a “metallic” core which governs the stability of the cluster ion (at least for not too high degree of halogenation).
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    URL: http://dx.doi.org/10.1007/BF01448338
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    Size effect in3He n aggregates. A Gutzwiller approach (1991)
    Springer
    The European physical journal 20 (1991), S. 273-276 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. +d ; 31.20.Tz ; 67.50. -b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Hubbard hamiltonian (where only intraatomic correlations between fermions are taken into account) is particularly well suited for the description of3He systems. It has already been used in the description of point defects (such as spin polarons) in the bulk. The variational Gutzwiller method is one of the most useful way for treating the Hubbard hamiltonian. This technique has been applied with success by Vollhardt to the bulk. We apply it here to aggregates. Our main results are the following: 1 existence of a critical size,N c , above which3He n begin to be stable; 2 calculation of the magnetic susceptibility. In this part two cases are studied: low magnetic field where only the density of states, σ(E F), at the Fermi level is needed and high magnetic field where the whole density of states is needed. The results are compared with other theoretical calculations.
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    URL: http://dx.doi.org/10.1007/BF01543990
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