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  • 1
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 5197-5200 
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 5126-5131 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Recently Perera and Berkowitz [J. Chem Phys. 96, 3092 (1992)] and Neria and Nitzan [J. Chem. Phys. 96, 5433 (1992)] carried out computer simulations of solvation dynamics of an ion in dense Stockmayer liquids. Both the simulations observed an ultrafast component which decays in a few tens of femtoseconds with a Gaussian time dependence. This is followed by a slow exponential-like decay with a time constant of a few picoseconds. It is shown here that many of the simulation results can be explained very well from a first principles theory with no adjustable parameter.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 8367-8377 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Both the equilibrium and the dynamical aspects of solvation of a classical ion in a dense binary dipolar liquid are investigated by using a molecular theory. The theory properly includes the differing inter- and intramolecular correlations that are present in a binary mixture. As a result, the theory can explain several important aspects of the nonideality of equilibrium solvation energy (broadly known as preferential solvation) observed in experiments. We find that the nonideality of solvation depends strongly on both the molecular size and the magnitude of the dipole moment of the solvent molecules. The interactions among the solvent molecules play an important role in determining the extent of this nonideality. The dynamical calculations are based on a generalized Smoluchowski equation which has been used extensively for studies in one component liquid. For binary liquid, our study reveals rich and diverse behavior such as dependencies on the sizes, the transport coefficients and the polar properties of the components. The theory offers a detailed picture of the dependence of the solvation dynamics on the composition of the mixture. It is predicted that the dynamics of solvation in a binary liquid is, in general, nonexponential and that the details of the dynamics can be quite different from those in a one component liquid. In particular, the continuum model is found to be grossly inaccurate in describing the solvation dynamics in binary mixtures and rather extreme conditions are needed to recover the predictions of the continuum model which can be attributed to the nonideality of the solvation. The predicted results are used to study the dynamic solvent effects on the rate of an adiabatic electron transfer reaction in a binary liquid. The theoretical predictions are also compared with the available experimental results.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 1955-1958 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The relationship between the microscopic orientational relaxation time (τm) and the collective, macroscopic relaxation time (τM) of a dipolar liquid has been a subject of considerable interest. We examine this relation for the kinetic Ising model of Glauber, used recently by Skinner to describe dielectric relaxation in glassy polymers. In this model, exact solutions for both the same spin and the collective spin time correlation functions are possible. We find that these two correlation functions are entirely different from each other. The self spin correlation function is highly nonexponential, as pointed out by Glauber and by Skinner. But, the collective spin relaxation is single exponential, and the wave vector and frequency dependent dielectric function is of simple Debye form. The reason for this difference is discussed.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6833-6839 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: It was recently proposed that collective polarization excitations, called dipolarons in analogy with the plasmons in the Coulomb systems, can exist for a long duration in a dense dipolar liquid. In this article, we present a microscopic analysis of the properties of such collective excitations, both at small and at intermediate wave vectors. The theory predicts the existence of dipolarons at values of the relevant parameters which are in good agreement with the computer simulation of Pollock and Alder. However, the predicted range of the parameter values in which the "true'' dipolaronic behavior is significant are rather too small to be important in common dipolar liquids like water, acetonitrile or methyl iodide. We find that the microscopic structure, especially the local orientational correlations and also the translational modes of the liquid, play important roles in determining the nature and the lifetime of the dipolaronic modes. Especially, these modes are more likely to occur at intermediate wave numbers if the translational contribution to the polarization relaxation is significant. The consequences of these theoretical predictions in experimental studies are discussed.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 3177-3182 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The dynamics of solvation of newly created charged species in dense dipolar liquids can proceed at a high speed with time constants often in the subpicosecond domain. The motion of the solvent molecules can be in the inertial limit at such short times. In this paper we present a microscopic study of the effects of inertial motion of solvent molecules on the solvation dynamics of a newly created ion in a model dipolar liquid. Interesting dynamical behavior emerges when the relative contribution of the translational modes in the wave-vector-dependent longitudinal relaxation time is significant. Especially, the theory predicts that the time correlation function of the solvation energy can become oscillatory in some limiting situations. In general, the dynamics becomes faster in the presence of the inertial contribution. We discuss the experimental situations where the inertial effects can be noticeable.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 6531-6536 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We investigate the plausible mechanism of fast decomposition of acetyl chloride upon 1nπ* (CO) excitation through the selective C–Cl bond-fission on the lowest excited singlet state surface using ab initio quantum chemical methods. Effects of zero point energy corrections and of electron correlation have been considered. The pathway involves dissociation, via a φClφ*CO and a φClφ*C–Cl configurations where φ's stand for wave functions of σ-molecular orbitals.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2068-2073 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: An approximate expression is derived for the dielectric function ε(k,ω). The theory includes inertial and non-Markovian effects and is free of adjustable parameters. For the k=0 case, detailed comparisons are made with computer simulation results for dipolar soft-sphere and Stockmayer fluids, and the theory is shown to be qualitatively sound at both low and high frequencies. The present approximation should be very useful in developing a theory of solvation dynamics which properly includes important inertial effects.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 4959-4966 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The dielectric behavior of model electrolyte solutions is studied by molecular dynamics simulations. For the systems considered, it is found that the zero-frequency dielectric constant depends only on equilibrium properties and that there is no measurable "kinetic dielectric decrement.'' A theoretical explanation of the simulation results is presented. It is argued that no kinetic dielectric decrement exists for spherical ions in solvents of arbitrary molecular symmetry.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 4926-4931 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A self contained microscopic theory is described for ion solvation dynamics in dipolar fluids. The theory takes account of inertial and non-Markovian effects which are of critical importance for the fast initial phase of the relaxation of the ion–solvent energy. The theory also includes diffusional effects important at long times. The results obtained are shown to be in good agreement with recent computer simulation studies of ions in Stockmayer solvents.
    Materialart: Digitale Medien
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