Noncrystalline structure of argon clusters. I. Polyicosahedral structure of ArN clusters, 20

Small argon clusters are produced in a free jet expansion and studied by electron diffraction. Due to their very low proportion in the beam sample in comparison to the monomers, the smallest detectable clusters contain about 20 atoms. When they grow up to some 50 atoms, they present the same noncrystalline structure. This structure is identical to that of solid models constructed during a molecular dynamics calculation by cooling a liquid drop of atoms interacting through a Lennard‐Jones potential. Because it is composed of icosahedra of 13 atoms, either joined one to the other either interpenetrating each other, this structure may be called polyicosahedral. The comparison between theoretical and experimental diffraction functions leads to an estimate of the cluster temperature 27±3 K and of the proportion of monomers in the beam. We discuss the similarity in the radial distribution functions of both PIC models and bulk amorphous materials, and give arguments for the stability of the clusters.

[1]  W. Wefelmeier,et al.  Ein geometrisches Modell des Atomkerns , 1937 .

[2]  L. Bartell,et al.  A High Precision Electron‐Diffraction Unit for Gases , 1954 .

[3]  K. Bier,et al.  Strahlen aus kondensierten Atomen und Molekeln im Hochvakuum , 1956 .

[4]  L. Verlet.  Computer "Experiments" on Classical Fluids. I. Thermodynamical Properties of Lennard-Jones Molecules , 1967 .

[5]  P. Audit.  Liaisons intermoléculaires dans les jets supersoniques. Étude par diffraction d'électrons , 1969 .

[6]  Roger Campargue,et al.  Aerodynamic Separation Effect on Gas and Isotope Mixtures Induced by Invasion of the Free Jet Shock Wave Structure , 1970 .

[7]  David Jackson McGinty,et al.  Vapor phase homogeneous nucleation and the thermodynamic properties of small clusters of argon atoms , 1971 .

[8]  M. Hoare,et al.  Physical cluster mechanics: Statics and energy surfaces for monatomic systems , 1971 .

[9]  L. B. Davies,et al.  An electron diffraction and resistivity study of non-crystalline thin films of gold and silver , 1972 .

[10]  W. Obert,et al.  Cluster Formation in Expanding Supersonic Jets: Effect of Pressure, Temperature, Nozzle Size, and Test Gas , 1972 .

[11]  J. Farges,et al.  Electron Difraction Unit with Supersonic Molecular Beam and Cluster Beam , 1973 .

[12]  J. Farges,et al.  Crystalline and noncrystalline effects in electron diffraction patterns from small clusters in an argon cluster beam , 1973 .

[13]  J. Sadoc,et al.  Theoretical calculation of dense random packings of equal and non-equal sized hard spheres applications to amorphous metallic alloys☆ , 1973 .

[14]  J. Wright,et al.  Structural investigations of amorphous transition element films I. Scanning electron diffraction study of cobalt , 1974 .

[15]  J. Wright,et al.  Structural investigations of amorphous transition element films: II. Chromium, iron, manganese and nickel , 1974 .

[16]  C. Briant,et al.  Icosahedral microclusters a possible structural unit in amorphous metals , 1978 .