STUDIES OF INTERACTION OF SMALL MOLECULES WITH WATER CONDENSED MEDIA<br /><br /> The present work reports experimental and theoretical studies of the intermolecular interactions in condensed water media. The chemical objects comprise pristine ice and polar organic substances: acetone, acetaldehyde, methanol and chloroform and bi-component water-organic deposits. The experimental part of the studies includes the Fourier Transform Infrared Reflection Absorption spectral (FTIR RAS) examination of the processes of film growth by vapor deposition on cold metal substrate and subsequent annealing. The theoretical studies include <em>ab initio</em> (<em>MP2</em>) and semi-empirical (<em>B3LYP</em>) calculations on the small water and water-organic clusters and classical molecular dynamics simulations of the adsorption of inert guests (Xe/Rn) on the ice surface. The FTIR RA spectral studies reveal that depending on the deposition conditions condensed water media exist in two principal structural forms: noncrystalline and polycrystalline. The former is characterized by porous structure while the latter exists as a non-porous medium with smooth external interface. On annealing, characteristic spectral changes indicate on a rapid crystallization occurring at a certain temperature range. The initial adsorption of organic molecules is accompanied by the hydrogen-bonded coordination between the functional group of organic species and non-coordinated hydroxyl group of the ice surface, the topology of which depends on the electronic properties of the functional group. The computational studies of small water-organic clusters reveal, in particular, two major coordination minima for carbonyl group: a single hydrogen-bonded in-plane complex and a double hydrogen-bonded in-plane complex. The classical molecular dynamics of Xe/Rn species on the ice interface is consistent with two distinctly different surface adsorption sites: one that delocalized over the entire surface and one that confined to small opening in the top ice layer, disrupted by the thermal molecular motion. The penetration barrier is associated with van der Walls repulsion of guest species from the ordered water hexagonal arrangement. A thermo-disruption of latter leads to a rapid diffusion of guest species inside ice medium.

The research presented in this dissertation pertains to the evaluation of stiffness of carbon nanotubes (CNTs) in a multiscale framework and modeling of the interfacial mechanical behavior in CNT-polymer nanocomposites. The goal is to study the mechanical behavior of CNTs and CNT-polymer interfaces at the atomic level, and utilize this information to develop predictive capabilities of material behavior at the macroscale. Stiffness of CNTs is analyzed through quantum mechanical (QM) calculations while the CNT-polymer interface is examined using molecular dynamics (MD) simulations. CNT-polymer-matrix composites exhibit promising properties as structural materials and constitutive models are sought to predict their macroscale behavior. The reliability of determining the homogenized response of such materials depends upon the ability to accurately capture the interfacial behavior between the nanotubes and the polymer matrix. In the proposed work, atomistic methods are be used to investigate the behavior of the interface by utilizing appropriately chosen atomistic representative volume elements (RVEs). Atomistic simulations are conducted on the RVEs to study mechanical separation with and without covalent functionalization between the polymeric matrix and two filler materials, namely graphite and a (12,0) Single Wall zig zag CNT. The information obtained from atomistic studies of separation is applicable for higher level length scale models as cohesive zone properties. The results of the present research have been correlated with available experimental data from characterization efforts.

The study of coherent states (CS) for a quantum mechanical system has received a lot of attention. The definition, applications, generalizations of such states have been the subject of work by researchers. A common starting point of all these approaches is the observation of properties of the original CS for the harmonic oscillator. It is well-known that they are described equivalently as (a) eigenstates of the usual annihilation operator, (b) from a displacement operator acting on a fundamental state and (c) as minimum uncertainty states. What we observe in the different generalizations proposed is that the preceding definitions are no longer equivalent and only some of the properties of the harmonic oscillator CS are preserved. In this thesis we propose to study a new class of coherent states and its properties. We note that in one example our CS coincide with the ones proposed by Glauber where a set of three requirements for such states has been imposed. The set of our generalized coherent states remains invariant under the corresponding time evolution and this property is called temporal stability. Secondly, there is no state which is orthogonal to all coherent states (the coherent states form a total set). The third property is that we get all coherent states by acting on one of these states ['fiducial vector'] with operators. They are highly non-classical states, in the sense that in general, their Bargmann functions have zeros which are related to negative regions of their Wigner functions. Examples of these coherent states with Bargmann function that involve the Gamma and also the Riemann ⲝ functions are represented. The zeros of these Bargmann functions and the paths of the zeros during time evolution are also studied.

Group 3 metal clusters are synthesized by laser vaporization in a pulsed cluster beam source and identified with laser ionization time-of-flight mass spectrometry. The adiabatic ionization energies and vibrational frequencies of these clusters are measured using mass-analyzed threshold ionization (MATI) spectroscopy. Their structures and electronic states are determined by combining the MATI spectra with quantum chemical calculations and spectral simulations. This dissertation focuses on the study of several small molecules, which include LaO2, La2, M2O2, M3O4, M3C2, and La3C2O, where M = Sc, Y, and La. Except for La2, these molecules exhibit strong ionic characters between the metal and oxygen or carbon atoms and can be described as [O-][La2+][O-], [M2+]2[O2-]2, [M8/3+]3[O2-]4, [M2+]3[C3-]2, and [La8/3+]3[C3-]2[O2-]. The interactions between the metal atoms form covalent bonds, which can be described by a triple bond in La2, a two-center two electron bond in M2O2, a three-center one electron bond in M3O4, and a three-center three electron bond in M3C2. In addition, the electron in the non-bonding highest occupied molecular orbital (HOMO) is localized in the La 6s orbital in LaO2 and La3C2O. The ground states of these molecules are all in low electron-spin states with the spin multiplicities of 1 or 2. Although the ground electronic state of LaO2 is a linear structure, the excited quartet state of the molecule is determined to be a bent structure. M2O2 and M3O4 have the planar rhombic and cage-like structures, respectively; whereas M3C2 has a trigonal bipyramid structure. La3C2O is formed by oxygen binding with two La atoms of La3C2. Ionization removes a metal-based (n+1)s electron in all neutral molecules, and the resultant ions have similar geometries to those of the corresponding neutral states. In the case of La2, additional ionization of a La 5d electron is also observed.

No description available.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24635号 / 工博第5141号 / 新制||工||1982(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 佐藤 啓文, 教授 作花 哲夫, 教授 寺村 謙太郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The study of coherent states (CS) for a quantum mechanical system has received a lot of attention. The definition, applications, generalizations of such states have been the subject of work by researchers. A common starting point of all these approaches is the observation of properties of the original CS for the harmonic oscillator. It is well-known that they are described equivalently as (a) eigenstates of the usual annihilation operator, (b) from a displacement operator acting on a fundamental state and (c) as minimum uncertainty states. What we observe in the different generalizations proposed is that the preceding definitions are no longer equivalent and only some of the properties of the harmonic oscillator CS are preserved. In this thesis we propose to study a new class of coherent states and its properties. We note that in one example our CS coincide with the ones proposed by Glauber where a set of three requirements for such states has been imposed. The set of our generalized coherent states remains invariant under the corresponding time evolution and this property is called temporal stability. Secondly, there is no state which is orthogonal to all coherent states (the coherent states form a total set). The third property is that we get all coherent states by acting on one of these states [¿fiducial vector¿] with operators. They are highly non-classical states, in the sense that in general, their Bargmann functions have zeros which are related to negative regions of their Wigner functions. Examples of these coherent states with Bargmann function that involve the Gamma and also the Riemann ¿ functions are represented. The zeros of these Bargmann functions and the paths of the zeros during time evolution are also studied. / Libyan Cultural Affairs

The study of waves and instabilities in quantum plasmas is of fundamental importance for understanding collective interactions in superdense astrophysical objects, in high intense laser-plasma/solid-matter interactions, in microelectronic devices and metallic nanostructures. In dense quantum plasmas, there are new pressure laws associated with the Fermi-Dirac distribution functions and new quantum forces associated with the quantum Bohm potential and the Bohr magnetization involving electron ½ spin. These forces significantly alter the collective behavior of dense quantum plasmas. This thesis contains six papers, considering several novel collective modes and instabilities at quantum scales. In Paper I, we have used the quantum hydrodynamical (QHD) model for studying the one-dimensional dust-acoustic (DA) waves incorporating the Fermi pressure law and the quantum Bohm potential. The latter modifies the DA wave dispersion relation in a collisional plasma. In Paper II, we have calculated the electrostatic potential of a test charge in an unmagnetized electron-ion quantum plasma. It is found that the Debye-Hückel and oscillatory wake potentials strongly depend upon the Fermi energy at quantum scales. The results can be of interest for explaining the charged particle attraction and repulsion in degenerate quantum plasmas, such as those in semiconductor and microelectronic devices. Paper III presents the parametric study of nonlinear electrostatic waves in two-dimensional collisionless quantum dusty plasmas. A reductive perturbation method has been employed to the QHD equations together with the Poisson equation, obtaining the cylindrical Kadomtsev-Petviashvili (CKP) equations and their stationary localized solutions. We have numerically examined the quantum mechanical and geometrical effects on the profiles of nonplanar quantum dust-ion-acoustic (DIA) and DA solitary waves. The role of static as well as mobile (negatively or positively charged) dust particles on the low-frequency electrostatic waves has also been highlighted for metallic nanostructures. Paper IV introduces the nonlinear properties of the ion-sound waves in a dense electron-ion Fermi magnetoplasma. The computational analysis of the nonlinear system reveals that the Sagdeev-like potential and the ion-sound density excitations are significantly affected by the wave direction cosine and the Mach number at quantum scales. Paper V considers the nonlinear interactions of electrostatic upper-hybrid (UH), ion-cyclotron (IC), lower-hybrid (LH), and Alfvén waves in a quantum magnetoplasma. The nonlinear dispersion relations have been analyzed analytically to obtain the growth rates for both the decay and modulational instabilities involving the dispersive IC, LH, and Alfvén waves. In Paper VI, we have identified a new drift-like dissipative instability in a collisional quantum plasma. The modified unstable drift-like mode can cause cross-field anomalous ion-diffusion at quantum scales.

CAETANO, Márcia de Windson Costa. Polimorfismo da Clorpropamida investigado através de Espectroscopia Vibracional. 2006. 141 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2006. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-05-21T22:22:40Z No. of bitstreams: 1 2006_dis_mwccaetano.pdf: 3508898 bytes, checksum: d30348bd90f71bc8902edd696cad9095 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-05-22T19:39:13Z (GMT) No. of bitstreams: 1 2006_dis_mwccaetano.pdf: 3508898 bytes, checksum: d30348bd90f71bc8902edd696cad9095 (MD5) / Made available in DSpace on 2015-05-22T19:39:13Z (GMT). No. of bitstreams: 1 2006_dis_mwccaetano.pdf: 3508898 bytes, checksum: d30348bd90f71bc8902edd696cad9095 (MD5) Previous issue date: 2006 / Chlorpropamide (C10H13ClN2O3S, (1-[4-chlorobenzenesulphonyl]-3-propyl urea)) is a drug used to treat type II diabetes (non-dependent of insulin), especially when the diabetes can not be controlled by alimentary regimes. The polymorphism of this drug is widely documented exhibiting at least five crystalline forms. In this work, we present a vibrational study of four of these polymorphs by using Raman, infrared and near-infrared spectroscopies. The objective of this vibrational investigation is to correlate the vibrational modes with the possible crystalline structures, as well as, to evaluate these methods as a tool for identification and quality control of raw materials and formulated products. In order to provide a detailed characterization we also applied thermal analyses and x-ray powder diffraction techniques to identify the crystalline forms. Finally, the assignment of the bands observed in the vibrational spectra in terms of the normal vibrational modes was performed with the help the quantum mechanical calculations based on the density functional theory. These results allow us to investigate the conformational stability of chlorpropamide establishing correlations with the polymorphism of this drug. / A clorpropamida (C10H13ClN2O3S, (1-[4-chlorobenzenesulphonyl]-3-propyl urea)) é uma droga usada para tratar o diabetes tipo II (não dependente da insulina), em particular em pessoas cujo diabetes não pode ser controlada só pelo regime alimentício. O polimorfismo desta droga se encontra amplamente documentado exibindo, pelo menos, cinco diferentes formas cristalinas. Neste trabalho apresentamos um estudo de quatro destes polimorfos através das espectroscopias Raman, infravermelho e infravermelho próximo. O objetivo desta investigação vibracional é estabelecer correlações entre os modos vibracionais e as possíveis estruturas cristalinas, além de avaliar estes métodos como ferramentas para a identificação e controle de qualidade das matérias primas e produtos formulados. No intuito de prover uma caracterização detalhada também empregamos análises térmicas e difração de raios- X para a identificação prévia das formas cristalinas. Finalmente, a classificação das bandas observadas nos espectros vibracionais em termos dos modos normais de vibração da molécula foi realizada com a ajuda de cálculos computacionais baseados na teoria do funcional de densidade. Estes resultados também nos permitiram investigar a estabilidade conformacional da clorpropamida e estabelecer correlações com o polimorfismo da mesma.

Recent years have shown a dramatic growth of research activity in searching of materials that exhibit nonlinear optical (NLO) behaviours. Later investigations have shown that molecule-based organic materials and biomaterials possess advantages in NLO characteristics. This thesis is devoted to the theoretical and experimental study of the second-order nonlinear optical properties of native and modified bacteriorhodopsins. A hybrid quantum mechanical/molecular mechanical-configuration interaction (QM/MM-CI) method has been used to determine the nonlinear behaviour of modified BR. The calculated structures are the ground state and M1 state of wild type BR, several BR variants, the BR mutants W86F, W189F, W182F, W138C, Y185F, and Y83F as well as a photoreceptor NpSRII. The first hyperpolarizability of two available BR mutants W86F and D85C has been determined by means of the HRS technique. The experimentally determined first hyperpolarizability value for the mutant W86F is in good agreement with that obtained theoretically. Simultaneously with the time-resolved absorption spectroscopy measurements, the time-dependent HRS measurements were performed. Changes in the HRS signal during the photocycle were detected. The kinetics of time-resolved HRS and flash spectroscopy measurements of BR and the BR mutants T46C, R225C, R227C, D96C, and D85C were compared. The obtained kinetic constant are comparable with those determined by means of absorption spectroscopy. However, an unexpected decrease in the HRS intensity during the M to N transition was observed. The program "MultiFit" (written in the Delphi environment) as well as data acquisition software (written in the C environment) can be found online at: http://repositorium.uni-osnabrueck.de/bitstream/urn:nbn:de:gbv:700-2008020119/4/MultiFit.zip and: http://repositorium.uni-osnabrueck.de/bitstream/urn:nbn:de:gbv:700-2008020119/5/TRAS.zip