http://dspace.nbuv.gov.ua:80/handle/123456789/117382 Mon, 13 Apr 2026 12:49:34 GMT 2026-04-13T12:49:34Z http://dspace.nbuv.gov.ua:80/bitstream/id/349015/ http://dspace.nbuv.gov.ua:80/handle/123456789/117382 http://dspace.nbuv.gov.ua:80/handle/123456789/120896 On the possible reason for superconductivity strengthening in multiwall carbon nanotubes Gaididei, Yu.B.; Loktev, V.M. Basing on the structural peculiarity of two-layer graphene which consists of translational and energetical nonequivalency of carbon atoms from different sublattices, it is shown that the density of long-wave electronic states at the Fermi level is finite (in contrast to the monolayer graphene). It is suggested that the same may be the reason why the critical temperature of superconducting transition in multiwall nanotubes more than ten times higher than in single-wall nanotubes. Sun, 01 Jan 2006 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120896 2006-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/120895 Exciton condensation in quantum wells Sugakov, V.I. The theory of exciton condensation is given in two-dimensional systems under suggestion that condensation occurs in really space and condensed phase arises as a result of an attractive interaction between excitons. Due to the finite value of exciton lifetime the sizes of exciton condensed phase regions are restricted and the condensed phase appears in a form of system of islands amid exciton gas. The joint solution of kinetic equations for island size and exciton diffusion equation in the space between islands has been obtained. The theory is applied to explanation of experimental manifestation of condensed phase in quantum wells and also to explanation of the periodical fragmentation, which was observed in luminescence spectrum from a ring around a laser spot in a crystal with double quantum wells. For such explanations the theory does not require the exciton Bose–Einstein condensation. Sun, 01 Jan 2006 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120895 2006-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/120894 The polymerization of acetylene on supported metal clusters Gilb, S.; Arenz, M.; Heiz, U. The polymerization of acetylene was studied by thermal programmed reaction on model catalysts consisting of size-selected Ag, Rh, and Pd atoms and Pdn (1 ≤ n ≤ 30) clusters on well-characterized MgO(111) thin films. In a single-pass heating cycle experiment, benzene, butadiene, and butane were catalyzed with different selectivities as function of cluster size: palladium and rhodium atoms selectively produce benzene, and the highest selectivity for butadiene is observed for Pd₆, whereas Pd₂₀ reveals the highest selectivity for butane. Ag atoms are inert. These results provide an atom-by-atom observation of the selectivity of small cluster catalysts. Sun, 01 Jan 2006 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120894 2006-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/120893 Desorption of water cluster ions from the surface of solid rare gases Tachibana, T.; Miura, T.; Arakawa, I. Electron or photon irradiation on H₂O adsorbed on the surface of rare gas solids induces the desorption of protonated water clusters, (H₂O)nH⁺. The yield and the size n distribution of cluster ions depend on the coverage, the deposition temperature of water and the thickness of a rare gas film. These results indicate that the (H₂O)nH⁺ ions are originated from the isolated water cluster and most important factor determining the size n distribution of desorbed (H₂O)nH⁺ is the sizes of water islands on rare gas solid. The measurement of kinetic energy distributions indicated that the desorbing energy of clusters depend on the rare gas species of the substrates and the cluster size. It is suggested that the (H₂O)nH⁺ desorption is due to Coulomb repulsion between the ionic water cluster and the rare gas ion. Sun, 01 Jan 2006 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120893 2006-01-01T00:00:00Z