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  • Comparison of the atomic level structure of the plastic crystalline and liquid phases of CBr2Cl2: Neutron diffraction and reverse Monte Carlo modelling

     Pothoczki, Szilvia; Temleitner, László; Pardo Soto, Luis Carlos; Cuello, Gabriel Julio; Rovira Esteva, Muriel; Tamarit Mur, Jose Luis
    Journal of physics: condensed matter
    Date of publication: 2013-10-18
    Journal article

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    Neutron diffraction results obtained for plastic crystalline dichlorodibromomethane (CBr2Cl2) have been modelled by means of the reverse Monte Carlo method. Comparison with its liquid phase is provided at several levels of the atomic structure (total scattering structure factors, partial radial distribution functions, orientational and dipole-dipole correlations). The results reveal that the relative orientation of neighbouring molecules largely depends on the steric effect. The small dipole moment does not have as strong an influence as the steric effect on the short-range order. Our observations fit well with earlier findings presented for the series CBr nCl4-n (n = 0, 1, 2, 4). © 2013 IOP Publishing Ltd.

  • Dynamic heterogeneity in the glass-like monoclinic phases of some halogen methane compounds

     Zuriaga, M. J.; Pérez, S. C.; Pardo Soto, Luis Carlos; Tamarit Mur, Jose Luis
    American institute of physics inc. , Conf. AIP. Proc. (15517616, 0094243X)
    Date of publication: 2013-02-25
    Journal article

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    In this work we study the heterogeneity of the dynamics on the low-temperature monoclinic phases of the simple molecular glassy systems , n = 0, 1, 2. In these systems the disorder comes exclusively from reorientational jumps mainly around the C3 molecular axes. The different time scales are determined by means of the analysis of the spin-lattice relaxation time obtained through Nuclear Quadrupole Resonance (NQR) technique. Results are compared with those obtained from dielectric spectroscopy, from which two a- and ß-relaxation times appear. NQR results enable us to ascribe with no doubt that the existence of two relaxations is due to dynamical heterogeneities which are the consequence of the different molecular surroundings of the molecules in the asymmetric unit cell of systems here studied. © 2013 American Institute of Physics Published online 25 febrero 2013

  • On the structure of water and chloride ion interactions with a peptide backbone in solution

     Busch, Sebastian; Pardo Soto, Luis Carlos; O'Dell, William B.; Bruce, Chrystal D.; Lorenz, Christian D.; McLain, Sylvia E.
    Physical chemistry chemical physics
    Date of publication: 2013-12-28
    Journal article

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    The arrangement of water and chloride ions around a model peptide (glycyl-l-prolyl-glycine-NH2) was investigated using Molecular Dynamics (MD) simulations and complementary Empirical Potential Structure Refinement (EPSR) simulations which adapt the modelled structure to reproduce experimentally measured neutron diffraction data. The results are in good qualitative agreement and show a common picture for all hydrogen-containing amine and amide groups: namely that there are two common chloride interactions observed-a direct contact between Cl- and peptide backbone and a water-mediated interaction. The geometry of this mediation depends on the distance between chloride and nitrogen and hints towards two distinct modes of interaction between water and the ion, either along one of the O-H bonds or along the water dipole. © 2013 the Owner Societies.

  • Dynamic heterogeneity in the glass-like monoclinic phases of some halogen methane compounds

     Zuriaga, M. J.; PÉREZ, S.C.; Pardo Soto, Luis Carlos; Tamarit Mur, Jose Luis
    Slow Dynamics in Complex Systems
    Presentation's date: 2012-12-03
    Presentation of work at congresses

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  • The picosecond dynamics of the phospholipid dimyristoylphosphatidylcholine in mono- and bilayers

     Busch, Sebastian; Pardo Soto, Luis Carlos; Smuda, Christoph; Unruh, Tobias
    Soft matter
    Date of publication: 2012-04-07
    Journal article

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  • Constraints on the mass and radius of the accreting neutron star in the Rapid Burster

     Sala Cladellas, Gloria; José Pont, Jordi; Parikh, Anuj Ramesh; Haberl, Frank; Longland, Richard Leigh; Pardo Soto, Luis Carlos; Andersen, M.
    Astrophysical journal
    Date of publication: 2012-06-20
    Journal article

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  • Polymorphism in halogen-ethane derivatives: CCl3-CF2Cl and CF3-CF2Cl

     Negrier, Philippe; Del Barrio Casado, Maria; Tamarit Mur, Jose Luis; Pardo Soto, Luis Carlos; Mondieig, Denise
    Crystal growth and design
    Date of publication: 2012-01-03
    Journal article

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    Molecular crystals of halogen–ethane derivatives C2X6–nYn (X = Cl, Y = F) are known to display order–disorder phase transitions involving changes of the translational, orientational, and conformational order. The appearance of a high-temperature orientationally disordered phase with a high symmetry lattice is expected for this set of compounds in view of their “pseudospherical” molecular geometry. In this work, we present a study of polymorphism of the compounds 1,1,1,2-tetrachloro-2,2-difluoroethane (CCl3–CF2Cl) and 1-chloro-1,1,2,2,2-pentafluoroethane (CF3–CF2Cl), in which conformational disorder is not present, by combining neutron (D2B and D1B instruments at the Laue-Langevin Institute) and X-ray scattering experiments. We show that despite the close molecular shapes and molecular structures of both compounds, strong differences concerning the disorder appear in the low-temperature phase. The low-temperature phase for CF3–CF2Cl is found to be fully ordered, with a monoclinic P21/n structure (Z = 4), while that of CCl3–CF2Cl is found to be orthorhombic Pmna (Z = 4) with a disorder concerning one Cl and one F sites, each one with a fractional occupancy of 50%. Details related to the high-temperature orientationally disordered phases (both body-centered-cubic) are also given.

  • Dynamic heterogeneity in the glass-like monoclinic phases of CBr nCl 4-n, n 0,1,2

     Zuriaga, M.; Perez, Silvina C.; Pardo Soto, Luis Carlos; Tamarit Mur, Jose Luis
    Journal of chemical physics
    Date of publication: 2012-08-07
    Journal article

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  • Role of steric and electrostatic effects in the short-range order of quasitetrahedral molecular liquids

     Pothoczki, Sz.; Ottochian, A.; Rovira Esteva, Muriel; Pardo Soto, Luis Carlos; Tamarit Mur, Jose Luis; Cuello, G.J.
    Physical review B: condensed matter and materials physics
    Date of publication: 2012-01-01
    Journal article

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    The study of how both steric and electrostatic interactions affect the structure of liquids formed by quasitetrahedral molecules has been undertaken in this work. We have studied trichlorobromomethane (CBrCl3) and dibromodichloromethane (CBr2Cl2), both displaying a dipole along their C3v and C2v molecular symmetry axes, respectively. The short-range order of the liquid state has been determined using neutron diffraction experiments that were modeled through the reverse Monte Carlo (RMC) technique. To study changes in steric effects due to the distortion of the tetrahedral symmetry, we have compared our results with a previous RMC modeling of carbon tetrachloride (CCl4). The subtle effects of the dipole in the structure of the liquid have been determined using a set of molecular dynamics simulations with and without atomic partial charges, being the force field validated via comparison with the diffraction data. In a first approximation, neither steric nor electrostatic interactions are able to modify the molecular ordering of a fully tetrahedral liquid such as CCl4. A more detailed analysis indicates that, although the interaction between dipoles does not have appreciable effects when aligned along the C3v molecular axes, as for the CBrCl3, it enhances the antiparallel orientation of dipoles when it is oriented along the C2v axes, as in the case of CBr2Cl2.

  • SPHERS, Jïlich's high-flux neutron backscattering spectrometer at FRM II

     Wuttke, Joachim; Budwig, Alfred; Drochner, Matthias; Kämmerling, Hans; Kayser, Franz-Joseph; Kleines, Harald; Ossovyi, Vladimir; Pardo Soto, Luis Carlos; Prager, Michael; Richter, Dieter; Schneider, Gerald J.; Schneider, Harald; Staringer, Simon
    Review of scientific instruments
    Date of publication: 2012-07-18
    Journal article

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    SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Jülich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ± 31 μeV, and a signal-to-noise ratio of up to 1750:1.

  • Dinámica en sólidos desordenados

     Romanini, Michela; Macovez, Roberto; Ruiz Martin, Maria Dolores; Levit Valenzuela, Rafael; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria; Vispa, Alessandro; Tamarit Mur, Jose Luis
    Participation in a competitive project

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    Emergence of glassy-like dynamics in an orientationally ordered phase  Open access

     Romanini, Michela; Negrier, Philippe; Tamarit Mur, Jose Luis; Capaccioli, Simone; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Mondieig, Denise
    Physical review B: condensed matter and materials physics
    Date of publication: 2012-04-04
    Journal article

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    The dynamics of a simple rigid pseudoglobular molecule (2-adamantanone) has been studied by means of dielectric spectroscopy and examined under the constraints imposed by the space group of the crystal structure determined by x-ray powder diffraction. The low-temperature monoclinic structure of 2-adamantanone, with one molecule per asymmetric unit (Z'= 1), displays a statistical intrinsic disorder, concerning the site occupancy of the oxygen atom along three different sites. Such a physically identifiable disorder gives rise to large-angle molecular rotations which inherently lead to time-average fluctuations of the molecular dipole, thus contributing to the dielectric susceptibility. The dielectric spectra for the low-temperature “ordered” phase displays a universal feature of glassy-like materials, i.e., coexistence of α- and β-relaxation processes. The former is clearly identified with the strongly restricted reorientational motions within the long-range “ordered” crystalline lattice. The latter, never observed before in fully translationally and highly orientationally ordered phases, displays all the properties of an original Johari-Goldstein β-relaxation, in spite of the strong character of this glass-like phase. These findings can be explained according to the coupling model, applied to such “ordered” phases.

  • Differences in first neighbor orientation behind the anomalies in the low and high density trans-1,2-dichlorothene liquid

     Rovira Esteva, Muriel; Murugan, N.A.; Pardo Soto, Luis Carlos; Busch, Sebastian; Tamarit Mur, Jose Luis; Cuello, G. J.; Bermejo, F.J.
    Journal of chemical physics
    Date of publication: 2012-03-28
    Journal article

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  • Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

     Krivchikov, A.I.; Korolyuk, O.A.; Sharapova, I.V.; Tamarit Mur, Jose Luis; Bermejo, F.J.; Pardo Soto, Luis Carlos; Rovira Esteva, Muriel; Ruiz Martin, Maria Dolores; Jezowski, A.; Baran, J.; Davydova, N. A.
    Physical review B: condensed matter and materials physics
    Date of publication: 2012-01-30
    Journal article

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    The thermal conductivity κ(T ) of the fully ordered stable phase II, the metastable phase III, the orientationally disordered (plastic) phase I, as well as the nonergodic orientational glass (OG) phase, of the glass former cyclohexanol (C6H11OH) has been measured under equilibrium vapor pressure within the 2–200 K temperature range. The main emphasis is here focused on the influence of the conformational disorder upon the thermal properties of this material. Comparison of results with those regarding cyanoclyclohexane (C6H11CN), a chemically related compound, serves to quantify the role played by the terminal groups -OH and -CN on the phonon scattering processes. The picture that emerges shows that motions of such groups do play a minor role as scattering centers, both within the low-temperature orientationally ordered phases as well as in the OG states. The results are analyzed within the Debye-Peierls relaxation time model for isotropic solids comprising mechanisms for long-wave phonon scattering within the OG and orientational ordered low-temperature phases, as well as others arising from localized short-wavelength vibrational modes as pictured by the Cahill-Pohl model. By means of complementary neutron and Raman scattering we show that in the OG state the energy landscapes for both compounds are very similar.

  • FABADA: a fitting algorithm for bayesian analysis of data

     Pardo Soto, Luis Carlos; Rovira Esteva, Muriel; Busch, S.; Ruiz Martin, Maria Dolores; Tamarit Mur, Jose Luis
    Journal of physics: conference series
    Date of publication: 2011-10-14
    Journal article

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  • Dynamics in Orientationally Disordered Solids  Open access  awarded activity

     Martinez Garcia, Julio Cesar
    Defense's date: 2011-07-15
    Department of Physics and Nuclear Engineering, Universitat Politècnica de Catalunya
    Theses

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    The key features of dynamics of ultraslowing glass forming systems are their universality in diversity. Its origin is recognized as one of the greatest challenges of condensed matter physics and materials engineering in the XXI century. Similar phenomena are observed on approaching the glass transition in low molecular weight supercooled liquids, polymers, colloidal fluids as well as in solids, for instance in orientationally disordered crystals, spin glass-like magnetic, vortex glasses. Pre-vitreous dynamics is also proposed as a general reference for the category of complex liquids/soft matter systems. The upsurge of the primary relaxation time or related dynamical properties is the basic physical phenomena of the still mysterious previtreous behavior. This means a much more pronounced slowing down than the Arrhenius pattern observed far above the glass transition temperature. Portraying this behavior constitutes one of key checkpoints for theoretical models developed to unwind the glass transition puzzle. However, none of the aforementioned features can answer the understanding that governs the increase of relaxation time in liquids upon cooling. In this thesis we focus on the above questions studying the dynamics of some materials for which their molecules can retain a translational order being orientationally disordered between them upon cooling, which are referred to plastic phases or orientationally disordered (OD) crystalline phases. The work presented in this thesis potentially extends the knowledge of dynamics of OD phases and orientationally glasses (OG), a research topic which has gained interest during the last decades. Through this study, especial attention has been devoted to the phenomenological equations accounting to the temperature dependence of the mean relaxation time describing the orientational dynamics .The study was carried out by the use of BDS as well as two complementary experimental techniques. We show distortion-sensitive and derivative-based empirical analysis of the validity of leading equations for portraying the previtreous evolution of primary relaxation time. A new method for studying the dynamics of glass forming systems is introduced and the minimization procedure is validated and discussed. We present the results divided in two topics, the dynamics of the pure compounds and mixed crystals and the derivative analysis through different existing models. In the first topic we focus on the dynamics of the pure compounds and mixed crystals formed between cycloheptanol and cyclooctanol as well as the a-relaxation dynamics of 1-cyano-adamantane and its mixtures with 1-chloro-adamantane. The second topic is divided in two groups of models, linearized and non-linearized models. In the linearized models we show the application of the derivative based, distortion-sensitive analysis to liquid crystals (LC) and OD phases. We also discuss the results concerning to the cases of the olygomeric liquid epoxy resin (EPON828), neopentylalcohol and neopentylglycol mixture, isooctylcyanobiphenyl and propylene carbonate. The possible empirical correlations between one of the linearized models with the universal pattern for the high frequency wing of the loss curve for primary relaxation time for LCs and OD phases is also shown. In the final part we show that the form of the equation recently introduced by Mauro et al. does not allow a similar straightforward linearization procedure. Unlike the previous models, the involved parameters are not correlated with the slope and the intercept of a linear function. In order to solve this problem, we have introduced the concept of the enthalpy space. The evidences of the existence of crossovers as well as quantitative descriptions are discussed. We show also a new procedure for detecting the crossover in a very easy way. A new kind of crossovers which seems to be impossible to be detected by the classical Stickel transformation is presented.

    La principal característica de la dinámica de sistemas vítreos viscosos, es su universalidad en la diversidad. Su origen es uno de los mayores desafíos de la física de la materia condensada y de la ingeniería de materiales en el siglo XXI. La fenomenología típica de las fases vítreas se observan cerca de la transición vítrea en líquidos subenfriados de bajo peso molecular, polímeros, fluidos coloidales, así como en los sólidos con fases orientacionalmente desordenadas. La imposibilidad de explicar las causas del gran aumento del tiempo de relajación al enfriar un líquido, constituye uno de los problemas más importantes no resueltos en materia condensada. Con el objetivo de dar respuesta a dicha interrogante, se han propuesto modelos termodinámicos y dinámicos que han resultado inconsistentes. En esta tesis nos centramos en dicha problemática, estudiando la dinámica orientacional de algunos materiales que al ser enfriados pueden conservar un orden traslacional mientras que se conserva el desorden orientacional de las moléculas que los forman. Dichas fases se conocen como fases plásticas u orientacionalmente desordenadas (OD). El trabajo presentado en esta tesis amplía el conocimiento de la dinámica de dichas fases, un tema de investigación cuyo interés ha aumentado durante las últimas décadas. Se ha dedicado una atención especial a las ecuaciones fenomenológicas que describen la dependencia del tiempo de relajación con la temperatura. El estudio se ha llevado a cabo mediante el uso de espectroscopía dieléctrica de banda ancha, así como mediante el uso de técnicas experimentales complementarias. Se ha introducido un nuevo método para el estudio de la dinámica de los sistemas que dan lugar a fases vítreas. El método ha sido validado y discutido. Los resultados de esta tesis se presentan divididos en dos temas, por un lado, la dinámica de compuestos puros y de los cristales mixtos y, por otro, el análisis mediante el método derivativo aplicado a los diferentes modelos físicos existentes. En el primer tema nos centramos en la dinámica de los compuestos puros y los cristales mixtos formados por cicloheptanol y ciclooctanol, así como la dinámica de la relajación alfa en 1-ciano-adamantano y sus mezclas con 1-cloro-adamantano. El segundo tema se divide en dos grupos de modelos, los modelos lineales y no lineales. En los modelos lineales se muestra la aplicación del procedimiento de derivativo en los cristales líquidos (CL) y las fases OD. También se discuten los resultados relativos a los casos de la resina líquida (EPON828), la mezcla neopentil-alcohol y neopentil-glicol, el carbonato de propileno, así como el CL isooctilcianobifenil. Se discute también la existencia de posibles correlaciones empíricas entre uno de los modelos lineales con el patrón universal para la parte de alta frecuencia de la curva de pérdidas dieléctricas de la relajación primaria para las fases CL y OD. En la parte final se muestra que la forma de la ecuación introducida recientemente por Mauro et al. no permite la linearización mediante el método derivativo. A diferencia de los modelos anteriores, los diferentes parámetros no están correlacionados con la pendiente y el origen de coordenadas de una función lineal. Para resolver este problema, hemos introducido el concepto del espacio entálpico. Se analiza también la existencia de cambios de comportamiento dinámicos y se aportan descripciones cuantitativas. Se muestra también un nuevo procedimiento para detectar los cambios dinámicos de una manera fácil, que permite incluso detectar aquéllos que son obviados mediante el método clásico de Stickel.

  • Universal critical-like scaling of dynamics in plastic crystals

     Martinez Garcia, Julio Cesar; Tamarit Mur, Jose Luis; Rzoska, S.J.; Droz-Rzoska, Aleksandra; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria
    Journal of non-crystalline solids
    Date of publication: 2011-01-15
    Journal article

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    Many theoretical models for the glassy dynamics have been proposed so far describing the changes in molecular dynamics along the extraordinary slowing down in the vitrification process of a disordered phase on cooling. Many of these theories share the concept of cooperative rearranging regions firstly proposed by Adam and Gibbs. Among them, the dynamical scaling model (DSM) is based on the random diffusion of free volume which creates random walking clusters formed by cooperatively rearranging entities. Within this framework a critical phenomenon relating a hidden phase transition at TC (below Tg) implies the divergence of the relaxation time (τ) or viscosity (η) τ, η ∝ (T − TC) − phi with a universal scaling exponent φ → 9. In this work we apply the DSM model to orientational glasses, obtained from the quenching of orientationally disordered phases (plastic crystals) via the application of the linearized derivative-based transformation of dielectric spectroscopy τ(T) data.

  • Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluorethane

     Rovira Esteva, Muriel; Murugan, A.; Pardo Soto, Luis Carlos; Busch, S.; Tamarit Mur, Jose Luis; Pothoczki, Sz.; Cuello, G. J.; Bermejo, F.J.
    Physical review B: condensed matter and materials physics
    Date of publication: 2011-08-18
    Journal article

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  • Secondary relaxations of orientationally disordered mixed crystals at temperatures lower than the glass transition temperature

     Martinez-Garcia, Julio C.; Tamarit Mur, Jose Luis; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria; Rzoska, S. J.; Drozd-Rzoska, A.
    Physica status solidi A. Applications and materials science (Print edition)
    Date of publication: 2011-06-16
    Journal article

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  • Fitting in a complex x2 landscape using an optimized hypersurface sampling

     Pardo Soto, Luis Carlos; Rovira Esteva, Muriel; Busch, S.; Moulin, J.F.; Tamarit Mur, Jose Luis
    Physical review E: statistical, nonlinear, and soft matter physics
    Date of publication: 2011-10-25
    Journal article

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  • Molecular Mechanism of Long-Range Diffusion in Phospholipid Membranes Studied by Quasielastic Neutron Scattering

     Busch, Sebastian; Smuda, Christoph; Pardo Soto, Luis Carlos; Unruh, Tobias
    Journal of the American Chemical Society
    Date of publication: 2010-02-17
    Journal article

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  • Microscopic structures and dynamics of high- and low-density liquid trans-1,2-dichloroethylene

     Rovira Esteva, Muriel; Murugan, Natarajan Arul; Pardo Soto, Luis Carlos; Busch, S.; Ruiz Martin, Maria Dolores; Appavou, M.S.; Tamarit Mur, Jose Luis; Smuda, C.; Unruh, T.; Bermejo, F.J.; Cuello, G. J.; Rzoska, S. J.
    Physical review B: condensed matter and materials physics
    Date of publication: 2010-03-08
    Journal article

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  • a-relaxation dynamics of orientationally disordered mixed crystals composed of Cl-adamantane and CN-adamantane

     Martinez Garcia, Julio Cesar; Tamarit Mur, Jose Luis; Capaccioli, Simone; Del Barrio Casado, Maria; Veglio, Nestor Raul; Pardo Soto, Luis Carlos
    Journal of chemical physics
    Date of publication: 2010-04-29
    Journal article

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    The α-relaxation dynamics of 1-cyano-adamantane (CNA) and its mixtures with 1-chloro-adamantane (ClA) has been studied by means of broadband dielectric spectroscopy. The existence of orientationally disordered (OD) face centered cubic mixed crystals (ClA1−XCNAX) for 0.5 ≤ X ≤ 1 has been put in evidence by thermodynamics and structural analyses. In addition to the OD phase of CNA, mixed crystals with compositions higher than the equimolar one exhibit a freezing of the orientational degrees of freedom into a glassy state, which involves also a strong increase of the antiferroelectric order at temperatures higher than the dielectric glass transition temperature. This experimental evidence is revealed by a stairlike effect in the variation of the Kirkwood factor with the temperature as a consequence of a twin effect in the dielectric strength without any anomaly in the temperature-density curves. The characteristic relaxation times are analyzed as a function of temperature and mole fraction. By setting a common temporal origin ("isochronal origin") at τ(Tg) = 100 s for each mole fraction, it emerges that the substitution of ClA molecules by those of CNA (diminution of X) gives rise to a slow down in the dynamics, despite that the molecular volume of ClA molecules are smaller than those of CNA. This fact goes along and is accompanied by a diminution of the lattice packing with the decrease of composition. It is also shown that the heterogeneities produced by the concentration fluctuations due to the chemical disorder are the main contribution to the non-exponential character of the α-relaxation peaks.

  • Disorder effects on heat transport properties of orientationally disordered crystals

     Sharapova, I.V.; Krivchikov, A.I.; Korolyuk, O.A.; Jezowski, A.; Rovira Esteva, Muriel; Tamarit Mur, Jose Luis; Pardo Soto, Luis Carlos; Ruiz Martin, Maria Dolores; Bermejo, F.J.
    Physical review B: condensed matter and materials physics
    Date of publication: 2010-03-30
    Journal article

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  • Cracks and pores ¿ their roles in the transmission of water confined in cementitious materials

     Bordallol, H.N.; Aldridge, L.P.; Wuttke, J.; Fernando, K.; Bertram, W.K.; Pardo Soto, Luis Carlos
    European physical journal. Special topics
    Date of publication: 2010-11-12
    Journal article

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  • Disentangling the secondary relaxations in the orientationally disordered mixed crystals: cycloheptanol plus cyclooctanol two-component system

     Martinez Garcia, Julio Cesar; Tamarit Mur, Jose Luis; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria; Rzoska, Syswester J.; Droz-Rzoska, Aleksandra
    Journal of physical chemistry B
    Date of publication: 2010-04-20
    Journal article

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    The dynamics of the pure compounds and mixed crystals formed between cycloheptanol (cC7-ol) and cyclooctanol (cC8-ol) has been studied by means of broadband dielectric spectroscopy at temperatures near and above the orientational glass transition temperature. Both compounds are known to display at least one orientationally disordered (OD) phase of simple cubic symmetry, and within this phase, a continuous formation of mixed crystals was demonstrated in the past (Rute, M. A. et al. J. Phys. Chem. B 2003, 107, 5914). The dielectric loss spectra of cC7-ol and cC8-ol show, in addition to the well-pronounced α-relaxation peaks with a continuous temperature shift (characteristic of the freezing of the molecular dynamics), secondary relaxations ( β and γ for cC8-ol and γ for cC7-ol) which are intramolecular in nature. The dynamics of several OD mixed crystals was recently studied (Singh, L. P.; Murthy, S. S. N. J. Phys. Chem. B 2008, 112, 2606), and surprisingly enough one of the secondary relaxations was not evidenced. We show here by means of a careful set of measurements for several mixed crystals and of a detailed analysis procedure the existence of the secondary relaxations for the mixed crystals. The results, moreover, doubtless reinforce the physical origin of each of the secondary relaxations.

  • Dynamics of orientationally disordered mixed crystal sharing Cl-adamantane and CN-adamantane

     Martinez Garcia, Julio Cesar; Capaccioli, Simone; Diez Berart, Sergio; Tamarit Mur, Jose Luis; Del Barrio Casado, Maria; Veglio, Nestor Raul; Pardo Soto, Luis Carlos
    Journal of non-crystalline solids
    Date of publication: 2010-01-27
    Journal article

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    Orientationally disordered (OD) mixed crystals formed between cyanoadamantane (CN-A) and chloroadamantane (Cl-A) have been thermodynamically characterized by means of thermal analysis and X-ray diffraction. The dynamics of these OD mixed crystals has been studied by means of broad band dielectric spectroscopy. Results evidence that dynamics of the α-relaxation process associated with the overall molecular tumbling slows down when molecules of CN-A are substituted by molecules of Cl-A.

  • Neutron diffraction as a tool to explore the free energy landscape in orientationally disordered phases

     Pardo Soto, Luis Carlos; Tamarit Mur, Jose Luis
    Date of publication: 2010-01-08
    Book chapter

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  • A procedure to quantify the short range order of disordered phase

     Pardo Soto, Luis Carlos; Tamarit Mur, Jose Luis
    Date of publication: 2010-01-08
    Book chapter

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  • Polimorphism of some halogen adamantane derivatives

     Negrier, Philippe; Levit Valenzuela, Rafael; Del Barrio Casado, Maria; Tamarit Mur, Jose Luis; Mondieig, D.; Pardo Soto, Luis Carlos
    Journées d'Études des Équilibres entre Phases
    Presentation's date: 2010-03-24
    Presentation of work at congresses

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  • Connecting the normal pressure equilibria of the two-component systemCCl(CH3)3 + CBrCl3 to the pressure¿temperature phase diagrams of purecomponents

     Del Barrio Casado, Maria; Tamarit Mur, Jose Luis; Céolin, R; Pardo Soto, Luis Carlos; Negrier, Philippe; Mondieig, D
    Chemical Physics
    Date of publication: 2009-03
    Journal article

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  • New Microscopic Mechanism for Secondary Relaxation in Glasses

     Zuriaga, M; Pardo Soto, Luis Carlos; Lunkenheimer, P; Tamarit Mur, Jose Luis; Veglio, N; Del Barrio Casado, Maria; Bermejo, F J; Loidl, and A
    Physical review letters
    Date of publication: 2009-08
    Journal article

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  • Disentangling the -relaxation in the bynary system cycloheptanol-cyclooctanol

     Martinez Garcia, Julio Cesar; Tamarit Mur, Jose Luis; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria; Veglio, Nestor Raul
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation's date: 2009-08-30
    Presentation of work at congresses

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  • Universal critical-like scaling of dynamics in plastic crystals

     Martinez Garcia, Julio Cesar; Tamarit Mur, Jose Luis; Rzoska, S J; Drozd-Rzoska, A; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation's date: 2009-08-30
    Presentation of work at congresses

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  • Hindered water motions in hardened cement pastes investigated over broad time and length scales

     Bordallo, H.N.; Aldridge, L.P.; Fouquet, P.; Pardo Soto, Luis Carlos; Unruh, T.; Wuttke, J.; Yokaichiya, F.
    ACS applied materials and interfaces
    Date of publication: 2009-09-25
    Journal article

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    We investigated the dynamics of confined water in different hydrated cement pastes with minimized contributions of capillary water. It was found that the water motions are extremely reduced compared to those of bulk water. The onset of water mobility, which was modified by the local environment, was investigated with elastic temperature scans using the high-resolution neutron backscattering instrument SPHERES. Using a Cauchy-Lorenz distribution, the quasi-elastic signal observed in the spectra obtained by the backscattering spectrometer was analyzed, leading to the identification of rotational motions with relaxation times of 0.3 ns. Additionally, neutron spin echo (NSE) spectroscopy was used to measure the water diffusion over the local network of pores. The motions observed in the NSE time scale were characterized by diffusion constants ranging from 0.6 to 1.1 × 10-9 m2 s-1 most likely related to water molecules removed from the interface. In summary, our results indicate that the local diffusion observed in the gel pores of hardened cement pastes is on the order of that found in deeply supercooled water. Finally, the importance of the magnetic properties of cement pastes were discussed in relation to the observation of a quasi-elastic signal on the dried sample spectra measured using the time-of-flight spectrometer.

  • Scaling the dynamics of orientationally disordered mixed crystals

     Romanini, Michela; Martinez Garcia, Julio Cesar; Tamarit Mur, Jose Luis; Rzoska, Sylwester J.; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Drozd-Rzoska, A.
    Journal of chemical physics
    Date of publication: 2009-11-14
    Journal article

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    The evolution of the primary relaxation time of orientationally disordered (OD) mixed crystals [(CH3)2C(CH2OH)2]1−X[(CH3)C(CH2OH)3]X, with 0

  • Dynamics of Restricted Reorientational Motions in Long-range Ordered Lattices

     Pardo Soto, Luis Carlos
    XII International Conference on the Physics of Non-Crystalline Solids
    Presentation's date: 2009-09-06
    Presentation of work at congresses

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  • Dynamics of an ergodic to non-ergodic phase transition within a long-range ordered phase

     Tamarit Mur, Jose Luis; Pardo Soto, Luis Carlos; Zuriaga, M; Lunkenheimer, P; Veglio, Nestor Raul; Bermejo, F J; Del Barrio Casado, Maria; Loidl, A
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation's date: 2009-08-30
    Presentation of work at congresses

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  • DINÁMICA DE SOLIDOS ORIENTACIONALMENTE DESORDENADOS

     Pardo Soto, Luis Carlos; Levit Valenzuela, Rafael; Macovez, Roberto; Martinez Garcia, Julio Cesar; Veglio, Nestor Raul; Ruiz Martin, Maria Dolores; Del Barrio Casado, Maria; Rovira Esteva, Muriel; Romanini, Michela; Tamarit Mur, Jose Luis
    Participation in a competitive project

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  • TRANSICIONS DE FASES, POLIMORFISME I DINÀMICA DE LA METAESTABILITAT

     Duarte Correa, Maria Jazmin; Rojas Gregorio, Jose Ignacio; Crespo Artiaga, Daniel; Torra Ferre, Vicenç; Pineda Soler, Eloy; Buti Papiol, Salvador; Salvado Cabre, Nativitat; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Ruiz Martin, Maria Dolores; Rovira Esteva, Muriel; Levit Valenzuela, Rafael; Veglio, Nestor Raul; Romanini, Michela; Macovez, Roberto; Flores Garcia, Juan Carlos; Torres Heredia, Victor Elias; Martinez Garcia, Julio Cesar; Serrano Gutierrez, Jorge; Molera Marimon, Judit; Tamarit Mur, Jose Luis
    Participation in a competitive project

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  • The pico- to nanosecond dynamics of phospholipids

     Pardo Soto, Luis Carlos
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation's date: 2009-08-30
    Presentation of work at congresses

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  • Two-component systems and pressure-temperature phase diagrams

     Tamarit Mur, Jose Luis; Del Barrio Casado, Maria; Levit Valenzuela, Rafael; Pardo Soto, Luis Carlos; Negrier, Philippe; Mondieig, D
    Journées d'Études des Équilibres entre Phases
    Presentation's date: 2009-04-01
    Presentation of work at congresses

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  • The new backscattering spectrometer SPHERES: current status and further optimisation

     Pardo Soto, Luis Carlos
    International Conference on Quasielastic Neutron Scattering
    Presentation's date: 2009-02-10
    Presentation of work at congresses

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  • Disordered effects in heat transport of a molecualar glassy crystal

     Sharapova, L V; Krivchicov, A I; KorolyukA, O A Jezowski; Pardo Soto, Luis Carlos; Rovira Esteva, Muriel; Tamarit Mur, Jose Luis; Bermejo, F J
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation's date: 2009-08-30
    Presentation of work at congresses

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  • Microscopic origin of liquid-liquid transition in 1,2-trans-dicholoroethylene

     Pardo Soto, Luis Carlos
    International Conference on Quasielastic Neutron Scattering
    Presentation's date: 2009-02-10
    Presentation of work at congresses

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  • The pico- to nanosecond dynamics of phospholipids

     Busch, S; Smuda, C; Schmiele, M; Pardo Soto, Luis Carlos; Unruh, T
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation of work at congresses

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  • Two-component system C13CBr+(CH3)3CBr

     Negrier, Philippe; Tamarit Mur, Jose Luis; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Mondieig, D.
    Journées d'Études des Équilibres entre Phases
    Presentation's date: 2009-04-01
    Presentation of work at congresses

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  • The Long-Range Motion of the Phospholipid DMPC in Mono- and Bilayers

     Pardo Soto, Luis Carlos
    International Conference on Quasielastic Neutron Scattering
    Presentation's date: 2009-02-10
    Presentation of work at congresses

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  • Disentangling the B-relaxation in the bynary system cycloheptanol-cyclooctanol

     Pardo Soto, Luis Carlos
    6th International Discussion Meeting on Relaxations in Complex Systems (6IDMRCS)
    Presentation's date: 2009-08-30
    Presentation of work at congresses

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  • Bayesian Analysis of QENS data: From parameter determination to model selection

     Pardo Soto, Luis Carlos
    International Conference on Quasielastic Neutron Scattering
    Presentation's date: 2009-02-10
    Presentation of work at congresses

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