Реферат: The heat capacity of the fullerite C60 has been investigated in the temperature interval 1-120 K using an adiabatic calorimeter. The fullerite is 99.99% pure. The sample mass is equal to about 0.6 g. Analysis of the obtained results and literature data [1-3] in the temperature range 1-300 K was carried out assuming that the translational, rotational, and intramolecular degrees of freedom make additive contributions to the heat capacity of fullerite.
Реферат: Investigations of thermal conductivity of dielectric crystals play a special role in solid state physics. The obtained information can be interesting both for theory and experiment. Introducing an impurity in the crystal enables to study influence of the thermal excitations modified by the impurity on the thermal conductivity or scattering of the heat carrier by the impurities. In CO-Ar solution the isotopic effect occurs, i.e. effect caused by the difference of the masses of the impurities and the host atoms. This leads to additional mechanism of phonon scattering.
Investigation of Al2O3 nanoparticle influence on caloric properties of isopropanol
Реферат: The aim of this work is the experimental studying the caloric properties of the model nanosystems - isopropyl alcohol with nanoparticles of alumina oxide (Al2O3) at different nanoparticle concentrations. Study of thermophysical properties of these model systems is required to assess the of nanoparticle\'s influence on the phase equilibria parameters and heat caloric properties of working fluids and coolants with nanoparticle additives promising for use in refrigeration systems.
Investigations of thermal properties of simple van der waals crystal based nanocomposites
Реферат: Physical properties of the objects featuring nanometric linear dimensions have been being intense investigated for over ten years. The reason for the scientific interest is twofold: basic science - the objects of dimensions of tens of nanometers display new physical properties, usually very much different than their macroscopic counterparts possible applications - the new properties of such the objects make it possible to design new devices. The nanostructured materials along with their new properties utilized as a base for new technologies have recently caused an unprecedented acceleration in some of their fields.
Low-frequency internal friction (LFIF) as express method for identification of cryocrystals in pores of the solids
Автор(ы): Leonteva A. V.*Erenburg A. I.*Prokhorov A. Yu.*
Реферат: Cryocrystals (solidified gases) form a relatively small group of materials which are gaseous at room temperatures and solids at low ones. They have the triple points at low temperatures because of low weight and small size of their molecules and also weakness of binding forces. This group of solids includes atomic cryocrystals (He, Ne, Ar, Kr, Xe), simplest molecular crystals (hydrogen, nitrogen, CO, oxygen, fluorine), and also few crystals from bigger molecules (CO2, N2O, CH4, NH3 etc.). Being chemically neutral, the gases fill the pores and becomes cryocrystals under cooling, influencing the properties of the solid matrices.
Magnetic resonance study of atomic hydrogen stabilized at high densities in solid H2 and D2 matrices
Автор(ы): Sheludiakov S.*Ahokas J.*Jarvinen J.*Zvezdov D.*Vainio О.*Lehtonen L.*Vasiliev S.*Mao S.*Khmelenko V. V.*Lee D. M.*
Реферат: Hydrogen and deuterium solids at low temperatures represent a special class of quantum crystals, where due to the large zero point oscillations and light mass, the effects of quantum tunnelling play important role. Behaviour of atomic impurities in these crystals attracts special attention due to possibility of reaching collective quantum phenomena related with Bose-Einstein Condensation (BEC) or so-called supersolidbehaviour. This may happen at high enough densities of atomic hydrogen.
Matrix-isolation studies of non-covalent interactions: more sophisticated approaches
Реферат: Matrix isolation is a powerful method to study non-covalent interactions, including hydrogen bonded species. The complexation effect is commonly analyzed by comparing vibrational spectra of the complex and the monomers. Most traditionally, molecular complexes in matrices are prepared by adding two species to the matrix gas and depositing the matrix at somewhat elevated temperatures and/or annealing the matrix after deposition. However, this general strategy is less suitable for the species that are difficult or impossible to prepare in the gas phase, for example, for highly reactive and unstable species. In addition, this method leads to relatively small amounts of the 1:1 complexes with an interference of monomers and larger clusters.
Mechanisms of self-screening in intrinsic semiconductors
Реферат: Electron-hole pairs (proton-hydroxyl pairs in water) thermally activated in intrinsic semiconductors interact through Coulomb forces which necessarily results in some self-screening that should either be accounted for in a proper way or shown to be negligible. Possible mechanisms of self-screening are considered in this work.
Melting of cryocrystasls at high pressures. Computer simulation
Реферат: Two types of molecular dynamics simulations: single-phase and two-phase carried out and applied to determine the melting temperatures of highly compressed diatomic cryocrystals: nitrogen and hydrogen, as functions of pressure. Solid hydrogen was modeled by two approximations (1) non-empirical atom-atom potential (AAP) approximation [1], and diatom-diatom (DDP) approximation. Within AAP-model potential energy of hydrogen molecules is represented as a function of interatomic distances between all atoms as a sum of intramolecular (bonding) and intermolecular (non-bonding) parts. Both types of potentials are expressed via known potential energies of two isolated hydrogen atoms in the singlet and triplet states.
Molecular dynamics simulation of thermodynamic and transport properties of H-bonded low-temperature substances
Автор(ы): Tychengulova A. J.*Aldiyarov A. U.*Drobyshev A. S.*
Реферат: The results of modeling of water clusters in nitrogen cryomatrix are presented. Earlier, our experimental studies of water in cryomatrix [1] have shown that changes in the concentration of an analyte in matrix leads to a splitting of the absorption bands characteristic frequencies of the molecules in the IR spectrum. Moreover the multiplicity of characteristic absorption bands in the IR spectrum remained unchanged during heating of the samples from the condensation temperature to the sublimation temperature of the matrix element.
