Dielectric Permeability of Nanocylinder

In the nanocylinder, a cut-off from the molecular crystal, dielectric permeability tensor is investigated. Excitons in the nanocylinder arise due to the exciting of the electron subsystem of the molecule. In evaluation of dielectric permeability Dzhyaloshinskii-Pitaevskii approach is used, connected with retarded and advanced exciton Green's functions and correct use of Paulion Green's function. It turned out that refraction and absorption indices depend on configuration coordinates, having maximal values at boundary cross-sections and minimal value at central cross-section of the nanocylinder broken symmetry structure. Although it was expected that boundary conditions make higher refractive and absorptive characteristics of the nanocylinder, this appeared not to be possible because Paulion Green's function is not proportional to the exciton concentration

Modified divergence theorem for analysis and optimization of wall reflecting cylindrical UV reactor

In this paper, the modified divergence theorem (MDT), known in earlier literature as the Gauss-Ostrogradsky theorem, was formulated and proposed as a general approach to electromagnetic (EM) radiation, especially ultraviolet (UV) radiation reactor modeling. A formulated mathematical model, based on MDT, for a multilamp UV reactor was applied to all sources in a reactor in order to obtain intensity profiles at chosen surfaces inside the reactor. Applied modification of MDT means that intensity at a real opaque or transparent surface or through a virtual surface, opened or closed, from different sides of the surface are added and not subtracted as in some other areas of physics. The derived model is applied to an example of the multiple UV sources reactor, where sources are arranged inside a cylindrical reactor at the coaxial virtual cylinder, having the radius smaller than the radius of the reactor. In this work, optimization of a reactor means maximum transfer of EM energy sources into the fluid for given fluid absorbance and fluid flow-dose product. The obtained results, for water quality known in advance, give a unique solution for an optimized model of a multilamp reactor geometry. As everyone can easily verify, MDT is a very good starting point for every reactor modeling and analysis

Phonon Contribution in Thermodynamics of Nano-Crystalline Films and Wires

Spectra of possible phonon states, as well as thermodynamic characteristics of nanocrystals (ultrathin film and quantum wire) of simple cubic crystalline structure are analyzed in this paper, using the method of two-time dependent Green functions. From energy spectra and internal energy of the system the thermal capacitance of these structures in low temperature region is found. The temperature behavior of specific heat is compared to that of corresponding bulk structure. It is shown that at extremely low temperatures thermal capacitance of quantum wire is considerably lower than the thermal capacitance 4 film as well as the bulk sample. Consequences of this fact are discussed in detail and its influence to thermodynamic properties of materials is estimated

Cylindrical quantum wires with hydrogen-bonded materials

Properties of cylindrical quantum wires are analysed in this paper. Energies of elementary excitations as well as one-particle wave functions were found for mentioned structure. For cylindrical quantum wires the temperature of phase transition was found. The behaviour of electric susceptibility in paraelectric phase was investigated.Comment: 10 page

Phonon contribution to heat capacitance of nanolayered crystalline structures

The paper presents the innovated method of two-time dependent Green's functions applied to the bounded and translational perturbed systems. Film-structures and super-lattices were analyzed by employing the phonon spectra for the calculation of relevant thermodynamic characteristics. Free energy and the internal energy of the system were found as well as the temperature behavior of layered structures. Heat capacitances of these nanostructures were compared to bulk ones. It was shown that heat capacitances of nanolayered structures in low-temperature region were higher than the same quantities of the corresponding bulk sample. In the middle and the highest temperature region, temperature behavior was inverse: heat capacitance of layered structures was lower than of the corresponding bulk ones. The consequences were discussed with relation to the ( super) conductive properties of nanomaterials

Fundamental Preferences of the Phonon Engineering for Nanostructural Samples

Application of nano-structures requires a knowledge of their fundamental physical (mechanical, electromagnetic, optical, etc.) characteristics. Thermodynamic properties associated with phonon displacements through the nano-samples are particularly interesting. Independent of the type of lattices, the thermodynamics of their subsystems (electrons, excitons, spin waves, etc.) is determined when the subsystem is in thermodynamic equilibrium with phonons. Phonons are collective mechanical oscillations of molecules or atoms and represent the most important system of excitations. Besides, the acoustical characteristics as well as conductive and superconductive properties etc. could not be realistically explained without phonons. All quoted is well known and all applications of phonons in bulk structures have been intensively exploited for more than a century. The fact which must be especially pointed out is that the role of phonons in nanostructures is much more impressive than in bulk structures. The main fact concerning phonon properties in nanostructures is the absence of the so-called acoustic phonons, i.e., phonons whose energy tends to zero when phonon momentum tends to zero. For the exciting of phonons in nanostructures activation energy different from zero is necessary. These unexpected characteristics require revision of all conclusions obtained by bulk theories of phonons. Therefore, the contribution of phonon subsystems to thermodynamic and energy transfering analysis is the first step in a research of nanostructure properties. This paper describes a major aspect of the effort to understand nanostructures, namely the study of phonons and phonon-mediated effects in structures with nanoscale dimensional confinement in one or more spatial dimensions. During the last two decades, there has been a steady effort to understand the optical and acoustic phonons in nanostructures such as the superlattice, quantum wires, nanotubes and quantum dots. The central theme of this paper is the description of the acoustic phonons of the optical type in these nanostructures. As a preliminary to describing the dispersion relations and mode structures for phonons in nanostructures, phonon amplitudes are quantized in terms of the harmonic oscillator approximation, and anharmonic effects leading to phonon decay are described in terms of the dominant phonon decay channels. These elastic and discontinued models are applied to describe the deformation potential and interactions in a variety of nanostructures. Dependence of energy on the wave vector is highly nonlinear and linear approximation of the laws of dispersion of phonons in small size nanostructures makes no sense. Changing the phonon dispersion law due to confinement severely affects the kinetic effects conditioned by the interaction of acoustic phonons with electrons, dotted defects, phonon-phonon interactions. Managing transport properties of acoustic phonons through the modification of their energy spectrum in nanostructures was named phonon engineering. In this paper we will try to observe the difference between the characteristics of different nano-crystalline structures: ultrathin films, composite films, i.e., superlattices, nanorods and quantum dots, we were interested in whether the quantum size effects (quantum confinement), quantum (de) coherence and influence of boundary conditions, strengthen or weaken in nanosamples. Finally, this paper describes how the dimensional confinement of phonons in nanostructures leads to modifications in the electronic, optical, acoustic, superconducting and thermodynamic properties of quantum. Thermal properties of nanostructures have recently attracted a lot of attention. The influence of size effects on thermal conductivity is becoming extremely important for device design and reliability. The problem of thermal management is even more severe for photonic devices such as vertical cavity surface emitting lasers. On the other hand, to improve performance of thermoelectrics, one needs to achieve low thermal conductivity. These are two contradictory demands, but both can be approached with appropriate modification of phonon modes, e.g., phonon engineering. On the basis of the calculated dispersion law and distribution of phonon states in nanoscopis crystals, free energy and entropy will be calculated. Internal energy as well as heat capacitance will also be analyzed. Low-temperature behavior of these quantities will be compared to the corresponding ones of bulk-structures. It was shown that heat capacitances of nano-layered structures in low-temperature region were higher than the same quantities of the corresponding bulk sample. In the middle and the highest temperature region, temperature behavior was inverse: heat capacitance of layered structures was lower than of the corresponding bulk ones. The consequences were discussed with relation to the better superconductive properties of nanomaterials

Theoretical explanation of light amplifying by polyethylene foil

In connection with the experimental result which stated that polyethylene foil amplifies about three times the penetrated light, we propose two theoretical explanations of this phenomenon. One of them is that several amplified peaks are the consequence of the forming of solitons in a polyethylene chain whose velocities are close to the velocity of sound. Forming of solitons, together with boundary conditions in a polyethylene macromolecules chain, which contain about thirty monomers, lead to the amplification of light. The second explanation requires introduction of homeopolar excitons in polymer macromolecules. Both energy gap of homeopolar excitons and width of homeopolar exciton zone are of the same order of magnitude. It means that transitions in a very wide zone give light quanta which are able to amplify the initial light. In order to avoid some confusion and misunderstandings, we wish to point out the following. Atoms and molecules as the whole are treated classically (transition through potential barriers, for example, etc.). The exception to this rule are phonon theories of crystals where the phonon is considered as a quanta of boson field, i.e., it means that, in the theory of mechanical oscillations, molecules and atoms as the whole are treated quantum mechanically. On the other hand, elementary excitations in crystals such as excitons, vibrons, spin waves, and ferroelectric excitations, etc., which arise from changes of some parts of atoms or molecules are treated quantum mechanically exclusively. In the analyses of this work, the excitations of an individual molecule subsystem (i.e. the quantum objects) would serve as an explanation of the light amplification by a polymer chain

Theoretical explanation of light amplifying by polyethylene foil

In connection with the experimental result which stated that polyethylene foil amplifies about three times the penetrated light, we propose two theoretical explanations of this phenomenon. One of them is that several amplified peaks are the consequence of the forming of solitons in a polyethylene chain whose velocities are close to the velocity of sound. Forming of solitons, together with boundary conditions in a polyethylene macromolecules chain, which contain about thirty monomers, lead to the amplification of light. The second explanation requires introduction of homeopolar excitons in polymer macromolecules. Both energy gap of homeopolar excitons and width of homeopolar exciton zone are of the same order of magnitude. It means that transitions in a very wide zone give light quanta which are able to amplify the initial light. In order to avoid some confusion and misunderstandings, we wish to point out the following. Atoms and molecules as the whole are treated classically (transition through potential barriers, for example, etc.). The exception to this rule are phonon theories of crystals where the phonon is considered as a quanta of boson field, i.e., it means that, in the theory of mechanical oscillations, molecules and atoms as the whole are treated quantum mechanically. On the other hand, elementary excitations in crystals such as excitons, vibrons, spin waves, and ferroelectric excitations, etc., which arise from changes of some parts of atoms or molecules are treated quantum mechanically exclusively. In the analyses of this work, the excitations of an individual molecule subsystem (i.e. the quantum objects) would serve as an explanation of the light amplification by a polymer chain

Metastable processes in proteins

We have transformed the Scott's model of protein Hamiltonian to metastable form, by means of double coherent unitary transformation. It turned out that in metastable Hamiltonian the number of quasi particles is not conserved due to the forming of pairs of excitations. The energies of pairs are found and their population is quoted. It is interesting that elementary excitations of metastable state behave similarly as excitations of molecular vibration field as well as excitations of electromagnetic field

Metastable processes in proteins

We have transformed the Scott's model of protein Hamiltonian to metastable form, by means of double coherent unitary transformation. It turned out that in metastable Hamiltonian the number of quasi particles is not conserved due to the forming of pairs of excitations. The energies of pairs are found and their population is quoted. It is interesting that elementary excitations of metastable state behave similarly as excitations of molecular vibration field as well as excitations of electromagnetic field