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1.
G. Grégoire M. Mons C. Dedonder-Lardeux C. Jouvet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):5-7
clusters (solvents being , or ) have been studied by resonance enhanced two photons ionization, leading to the detection of clusters. When water is the solvent, large clusters up to n>50 can be observed, whereas for and no clusters larger than 10 could be evidenced. Because the first step in the ionization process is the excitation from the
ground solvated () ion pair state to a covalent excited state, the differences in the cluster size distribution for different solvent may be
interpreted as a difference in cluster structures leading to a difference in the charge separation in the ground state.
Received: 30 September 1997 / Revised in final form: 30 October 1997 / Accepted: 30 October 1997 相似文献
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3.
V. Boutou A.R. Allouche F. Spiegelmann J. Chevaleyre M. Aubert Frécon 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(1):63-73
The geometrical structure of ground state Ban clusters (n
=2-14) has been predicted from various types of calculations including two ab initio approaches used for the smaller sizes namely HF+MP2(
n
=2-6), DFT (LSDA)(
n
=2-6, 9) and one model approach HF+pairwise dispersion used for all sizes investigated here. The lowest energy configurations
as well as some isomers have been investigated. The sizes n
=4, 7 and 13 are predicted to be the relatively more stable ones and they correspond to the three compact structures: the tetrahedron,
the pentagonal bipyramid and the icosahedron. The growth behavior from Ba7 to Ba13 appears to be characterized by the addition of atoms around a pentagonal bipyramid leading to the icosahedral structure of
Ba13 which is consistent with the observed size-distribution of barium clusters. Values for vertical ionization potentials calculated
for n
=2-5 at the CI level are seen to be in quite good agreement with recent measures.
Received: 14 May 1997 / Received in final form: 2 February 1998 / Accepted: 27 February 1998 相似文献
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5.
J. Akola A. Rytkönen H. Häkkinen M. Manninen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):93-99
The ionization potential of sodium clusters () at a finite temperature is studied using density functional theory and ab initio molecular dynamics. The threshold regions of the photoionization efficiency curves are deduced from the integrated IP distributions,
which are obtained from the energy eigenvalues of the highest occupied Kohn-Sham states during molecular dynamics by applying
a theoretically well-defined shift. The calculated ionization potentials are directly compared to the experimental values.
The energetically best geometry of Na55 is found to be a slightly distorted icosahedron.
Received 16 April 1999 and Received in final form 6 July 1999 相似文献
6.
F. Despa W. Bouwen F. Vanhoutte P. Lievens R.E. Silverans 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(3):403-411
The influence of doping of Li-clusters by electronegative O and C atoms on the ionization potentials was investigated. Experimentally,
we report ionization potentials for bare Lin clusters deduced from photoionization efficiency spectra. The values are compared with the results for LinO and LinC clusters. Observed differences are largely attributed to a quantum size effect caused by the segregated molecular part around
the impurity, which changes the electron work function. Theoretically, the Fermi and exchange-correlation energies which enter
the work function, are calculated in the frame of the augmented plane wave (APW) method by taking explicitly into account
the presence of the molecular core. The other contribution to the work function, the moment of the double layer at the cluster
surface, is computed by solving the corresponding Poisson's equation.
Received 9 September 1999 and Received in final form 7 February 2000 相似文献
7.
K. Hashimoto M. Okamoto K. Takayanagi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(1):75-78
The stability of neutral, singly and multiply ionized silicon clusters, (N
= 2-7, M
= 0, , , ), has been investigated using an ab initio density functional method. We show that the fragmentation effect significantly affects the structure of mass-spectra of multiply
ionized silicon clusters. For clusters, the clusters with a large fragmentation energy are found to correspond to the high peaks at N = 4 and 6 in mass-spectra. For clusters, a peak at N = 5 in mass-spectra has been predicted to be especially high.
Received: 9 June 1997 / Revised: 8 January 1998 / Accepted: 25 February 1998 相似文献
8.
E. Fort F. Pradère A. De Martino H. Vach M. Châtelet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):79-84
We present two complementary techniques that provide detailed diagnostics of supersonic beams involving several species. First,
surface scattering, together with quadrupole mass spectrometer detection, yields the monomer percentage for each species within
the beam. Second, analyses of beam profiles for different masses after scattering by a buffer gas permit determination of
mixed cluster presence and, if any, of cluster sizes and compositions. The two techniques are applied to supersonic expansions
of an argon-nitrogen mixture. We discuss the results that provide new insight in binary nucleation processes.
Received: 6 October 1997 / Revised: 4 November 1997 / Accepted: 13 November 1997 相似文献
9.
K. Hamada T. Wada C. Guet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):359-368
Stability of highly charged metal clusters in the electric field of an external ion is investigated with the classical liquid
drop model. We study the optimum shape of the cluster which has a local minimum of the total energy, taking account of the
effects of the surface charge polarization on the Coulomb energy and the cluster deformation on the surface energy. We find
that the cluster deformation greatly affects the total energy of the system and that a cluster with a fissility larger than
some critical value 0.7-0.8 can become unstable against deformation. We investigate the local competition between the Coulomb
force and the surface tension at the cluster surface and show that the surface charge polarization which is induced by the
external electric field significantly affects the shape of the cluster and its stability.
Received 5 November 2002 / Received in final form 27 January 2003 Published online 11 March 2003
RID="a"
ID="a"e-mail: hamada@konan-u.ac.jp 相似文献
10.
R. Guirado-López D. Spanjaard M.-C. Desjonquères A.M. Oleś 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(4):437-446
We analyze the stability of magnetic states obtained within the tight-binding model for cubooctahedral (Oh) and icosahedral (Ih) clusters of early 4d (Y, Zr, Nb, Mo, and Tc) transition metals. Several metastable magnetic clusters are identified which suggests the existence
of multiple magnetic solutions in realistic systems. A bulk-like parabolic behavior is observed for the binding energy of
Oh and Ih clusters as a function of the atomic number along the 4
d-series. The charge transfer on the central atom changes sign, while the average magnetic moments present an oscillatory behavior
as a function of the number of d electrons in the cluster. Our results are in agreement with other theoretical calculations.
Received: 20 November 1997 / Received in final form: 9 March 1998 / Accepted: 30 March 1998 相似文献
11.
J.M. Mestdagh M. Berdah N. Auby C. Dedonder-Lardeux C. Jouvet S. Martrenchard-Barra D. Solgadi J.P. Visticot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):291-302
The photodissociation of a chlorine molecule in the environment of a xenon cluster has been studied experimentally using the
real time pump and probe technique through the formation of an XeCl reaction product. The photodissociating system is probed
in such a way that the movement of a single chlorine atom in the xenon environment is detected. Various XenCl2 cluster sizes have been investigated leading to the distinction between uncapped, half-capped and doubly capped structures
for these clusters. These structures have a profound influence on the photodissociation dynamics. Retrapping of one chlorine
atomic fragment and stabilization of the XeCl reaction product is only observed for the half and doubly capped clusters. The
experimental work is complemented by classical molecular dynamics calculations to get a full picture of the photodissociation.
Received: 17 February 1998 / Received in final form and Accepted: 28 July 1998 相似文献
12.
M. Bertolus V. Brenner P. Millié 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(2):197-205
A theoretical study of clusters with using density functional theory is presented. Tests of various functionals demonstrate that local spin density approximation
(LSDA) is the most adequate functional for the study of these systems. Structures, vibrational frequencies, and IR intensities
of the lowest energy isomer of the studied clusters obtained using LSDA are described, and the unusual properties of the Si-C
clusters are discussed. A quantitative analysis of the obtained structures was carried out, and relations between the coordinations,
interatomic distances, and angles observed in the Si-C clusters were obtained through introduction of the notion of coordination.
This analysis also shows that the carbon atoms mainly exhibit sp and sp2 hybridizations, and that a majority of silicon atoms do not hybridize. This study is the fi
rst step of the implementation of a semi-empirical potential, which would describe the moderately small Si-C clusters.
Received: 20 October 1997 / Received in final form: 16 December 1997 / Accepted: 17 December 1997 相似文献
13.
14.
Ajeeta Dhavale D.G. Kanhere C. Majumder G.P. Das 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(4):495-500
The ground-state geometries, energetics and the stability of
(
n
=1-12) clusters are studied using ab initio molecular dynamics method. Our results indicate that the ground-state geometries of large clusters () are different from those of clusters where a trivalent impurity Al is added to the same monovalent host Na. Other features observed are an early appearance
of 3-dimensional structure and a pentagonal growth path from n
=6 up to n
=11. As expected, the ground-state geometry of is not an icosahedron but can be viewed as a distorted form of one of the low lying geometries of cluster. In the energetically favored structures impurity atom Mg is never located at the center of the cluster. The stability
analysis based on the energetics shows (8 valence electrons) to be the most stable. In addition there is a remarkable even-odd pattern observed in the dissociation
energy and the second difference in energy which is absent in earlier studies of and clusters.
Received: 16 September 1998 / Received in final form: 15 February 1999 相似文献
15.
M.L. Gardel R. Vandenbosch B.P. Henry C. Cooper D.I. Will 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):79-81
The destruction cross-section for 22.5 and 50 keV C1- , for 10 and 50 keV C8
1- and for 50 and 75 keV C60
1- clusters in collisions with H2 has been measured by an attenuation method. The destruction of the cluster anions is dominated by electron detachment rather
than fragmentation and is of the order of the geometric cross-section. The cross-sections vary little with bombarding energy.
Received: 16 September 1998 / Received in final form: 23 February 1999 相似文献
16.
X. Campi H. Krivine N. Sator E. Plagnol 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):233-238
We show that the size distributions of fragments created by high energy nuclear collisions are remarkably well reproduced
within the framework of a parameter free percolation model. We discuss two possible scenarios to explain this agreement and
suggest that percolation could be an universal mechanism to explain the fragmentation of simple fluids. Experiments with atomic
clusters would help to confirm this hypothesis.
Received 26 October 1999 and Received in final form 4 January 2000 相似文献
17.
P.-G. Reinhard E. Suraud 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):315-322
We use time-dependent density functional theory coupled to molecular dynamics for ionic motion to compute the spectra of ionic
vibrations in small Na clusters. Comparison with results from the distance dependent tight-binding approach shows good agreement
between these two very different methods. We discuss the evolution of the spectra with cluster size and charge and the impact
of ionic vibrations on the optical response.
Received 23 July 2001 / Received in final form 5 July 2002 Published online 8 October 2002
RID="a"
ID="a"e-mail: suraud@irsamc.ups-tlse.fr 相似文献
18.
B. Farizon M. Farizon M.J. Gaillard F. Gobet C. Guillermier M. Carré J.P. Buchet P. Scheier T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(1):5-8
We report the first account of a cluster fragmentation study involving high energy cluster-cluster collisions in which all
the fragments of each collision occurring in the experiment are mass analyzed on an event by event basis. This allows an unbiased
look at the true nature of fragmentation including a statistical analysis in terms of fluctuations in the fragment size distribution.
Received: 8 September 1998 / Revised and Accepted: 10 November 1998 相似文献
19.
A. Rytkönen M. Manninen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):351-357
The effect of melting transition on the ionization potential has been studied for sodium clusters with 40, 55, 142, and 147
atoms, using ab initio and classical molecular dynamics. Classical and ab initio simulations were performed to determine the ionization potential of Na142 and Na147 for solid, partly melted, and liquid structures. The results reveal no correlation between the vertical ionization potential
and the degree of surface disorder, melting, or the total energy of the cluster obtained with the ab initio method. However, in the case of 40 and 55 atom clusters, the ionization potential seems to decrease when the cluster melts.
Received 1st November 2002 Published online 24 April 2003
RID="a"
ID="a"e-mail: ar@phys.jyu.fi 相似文献
20.
M. Goldman 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(2):147-156
We describe the theory of EPR in a crystal field multiplet under sample spinning. Berry phases arise because the crystal field
is of lower symmetry than the full rotation group. The formal development is limited to pure J multiplets, crystal field doublets, and field and rotation axes parallel to a principal axis.
Received: 4 August 1997 / Received in final form: 19 December 1997 /
Accepted: 28 January 1998 相似文献