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Mallamace F, Mensitieri G, Salzano de Luna M, Lanzafame P, Papanikolaou G, Mallamace D. The Interplay between the Theories of Mode Coupling and of Percolation Transition in Attractive Colloidal Systems. Int J Mol Sci 2022; 23:5316. [PMID: 35628124 PMCID: PMC9141735 DOI: 10.3390/ijms23105316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 12/04/2022] Open
Abstract
In the recent years a considerable effort has been devoted to foster the understanding of the basic mechanisms underlying the dynamical arrest that is involved in glass forming in supercooled liquids and in the sol-gel transition. The elucidation of the nature of such processes represents one of the most challenging unsolved problems in the field of material science. In this context, two important theories have contributed significantly to the interpretation of these phenomena: the Mode-Coupling theory (MCT) and the Percolation theory (PT). These theories are rooted on the two pillars of statistical physics, universality and scale laws, and their original formulations have been subsequently modified to account for the fundamental concepts of Energy Landscape (EL) and of the universality of the fragile to strong dynamical crossover (FSC). In this review, we discuss experimental and theoretical results, including Molecular Dynamics (MD) simulations, reported in the literature for colloidal and polymer systems displaying both glass and sol-gel transitions. Special focus is dedicated to the analysis of the interferences between these transitions and on the possible interplay between MCT and PT. By reviewing recent theoretical developments, we show that such interplay between sol-gel and glass transitions may be interpreted in terms of the extended F13 MCT model that describes these processes based on the presence of a glass-glass transition line terminating in an A3 cusp-like singularity (near which the logarithmic decay of the density correlator is observed). This transition line originates from the presence of two different amorphous structures, one generated by the inter-particle attraction and the other by the pure repulsion characteristic of hard spheres. We show here, combining literature results with some new results, that such a situation can be generated, and therefore experimentally studied, by considering colloidal-like particles interacting via a hard core plus an attractive square well potential. In the final part of this review, scaling laws associated both to MCT and PT are applied to describe, by means of these two theories, the specific viscoelastic properties of some systems.
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Affiliation(s)
- Francesco Mallamace
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 00185 Rome, Italy
| | - Giuseppe Mensitieri
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy; (G.M.); (M.S.d.L.)
| | - Martina Salzano de Luna
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy; (G.M.); (M.S.d.L.)
| | - Paola Lanzafame
- Departments of ChiBioFarAm and MIFT—Section of Industrial Chemistry, University of Messina, CASPE-INSTM, V.le F. Stagno d’Alcontres 31, 98166 Messina, Italy; (P.L.); (G.P.)
| | - Georgia Papanikolaou
- Departments of ChiBioFarAm and MIFT—Section of Industrial Chemistry, University of Messina, CASPE-INSTM, V.le F. Stagno d’Alcontres 31, 98166 Messina, Italy; (P.L.); (G.P.)
| | - Domenico Mallamace
- Departments of ChiBioFarAm—Section of Industrial Chemistry, University of Messina, CASPE-INSTM, V.le F. Stagno d’Alcontres 31, 98166 Messina, Italy;
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A Combined Atomic and Molecular Probe Characterization of Aromatic Hydrocarbons via PALS and ESR: Methylbenzene. MATERIALS 2022; 15:ma15020462. [PMID: 35057182 PMCID: PMC8777640 DOI: 10.3390/ma15020462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 12/27/2021] [Accepted: 01/05/2022] [Indexed: 01/27/2023]
Abstract
A combined study of one of the simplest aromatic hydrocarbons, i.e., methylbenzene (toluene) (TOL), via the annihilation of an ortho-positronium (o-Ps) probe via positron annihilation lifetime spectroscopy (PALS) and the rotation dynamics of nitroxide spin probe 2,2,6,6-tetramethyl-piperidinyl-1-oxy (TEMPO) using electron spin resonance (ESR) over a wide temperature range, 10–300 K, is reported. The o-Ps lifetime, τ3, and the relative o-Ps intensity, I3, as a function of temperature exhibit changes defining several characteristic PALS temperatures in the slowly and rapidly cooled samples. Similarly, the spectral parameter of TEMPO mobility in TOL, 2Azz‘, and its correlation time, τc, reveal several effects at a set of the characteristic ESR temperatures, which were determined and compared with the PALS results. Finally, the physical origins of the changes in free volume expansion and spin probe mobility are revealed. They are reflected in a series of the mutual coincidences between the characteristic PALS and ESR temperatures and appropriate complementary thermodynamic and dynamic techniques.
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Caracciolo F, Carretta P, Filibian M, Melone L. Dynamic Nuclear Polarization of β-Cyclodextrin Macromolecules. J Phys Chem B 2017; 121:2584-2593. [PMID: 28260385 DOI: 10.1021/acs.jpcb.7b00836] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1H dynamic nuclear polarization and nuclear spin-lattice relaxation rates have been studied in amorphous complexes of β-cyclodextrins doped with different concentrations of the TEMPO radical. Nuclear polarization increased up to 10% in the optimal case, with a behavior of the buildup rate (1/TPOL) and of the nuclear spin-lattice relaxation rate (1/T1n) consistent with a thermal mixing regime. The temperature dependence of 1/T1n and its increase with the radical concentration indicate a relaxation process arising from the modulation of the electron-nucleus coupling by the glassy dynamics. The high-temperature relaxation is driven by molecular motions, and 1/T1n was studied at room temperature in liquid solutions for dilution levels close to the ones typically used for in vivo studies.
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Affiliation(s)
- Filippo Caracciolo
- Department of Physics, University of Pavia , Via Bassi 6, 27100 Pavia, Italy
| | - Pietro Carretta
- Department of Physics, University of Pavia , Via Bassi 6, 27100 Pavia, Italy
| | - Marta Filibian
- Department of Physics, University of Pavia , Via Bassi 6, 27100 Pavia, Italy
| | - Lucio Melone
- Department of Chemistry, Materials, and Chemical Engineering G. Natta, Politecnico of Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy.,E-campus University , Via Isimbardi 10, 22060 Novedrate, Como, Italy
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4
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Novikov V. Connection between the glass transition temperature T and the Arrhenius temperature T in supercooled liquids. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Tu W, Chen Z, Li X, Gao Y, Liu R, Wang LM. Revisiting the glass transition and dynamics of supercooled benzene by calorimetric studies. J Chem Phys 2015; 143:164501. [PMID: 26520521 DOI: 10.1063/1.4933425] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The glass transition and dynamics of benzene are studied in binary mixtures of benzene with five glass forming liquids, which can be divided into three groups: (a) o-terphenyl and m-xylene, (b) N-butyl methacrylate, and (c) N,N-dimethylpropionamide and N,N-diethylformamide to represent the weak, moderate, and strong interactions with benzene. The enthalpies of mixing, ΔH(mix), for the benzene mixtures are measured to show positive or negative signs, with which the validity of the extrapolations of the glass transition temperature T(g) to the benzene-rich regions is examined. The extrapolations for the T(g) data in the mixtures are found to converge around the point of 142 K, producing T(g) of pure benzene. The fragility m of benzene is also evaluated by extrapolating the results of the mixtures, and a fragility m ∼ 80 is yielded. The obtained T(g) and m values for benzene allow for the construction of the activation plot in the deeply supercooled region. The poor glass formability of benzene is found to result from the high melting point, which in turn leads to low viscosity in the supercooled liquid.
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Affiliation(s)
- Wenkang Tu
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Zeming Chen
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Xiangqian Li
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Yanqin Gao
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Riping Liu
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Li-Min Wang
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
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6
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Zhang R, Schweizer KS. Theory of activated penetrant diffusion in viscous fluids and colloidal suspensions. J Chem Phys 2015; 143:144906. [PMID: 26472397 DOI: 10.1063/1.4932679] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We heuristically formulate a microscopic, force level, self-consistent nonlinear Langevin equation theory for activated barrier hopping and non-hydrodynamic diffusion of a hard sphere penetrant in very dense hard sphere fluid matrices. Penetrant dynamics is controlled by a rich competition between force relaxation due to penetrant self-motion and collective matrix structural (alpha) relaxation. In the absence of penetrant-matrix attraction, three activated dynamical regimes are predicted as a function of penetrant-matrix size ratio which are physically distinguished by penetrant jump distance and the nature of matrix motion required to facilitate its hopping. The penetrant diffusion constant decreases the fastest with size ratio for relatively small penetrants where the matrix effectively acts as a vibrating amorphous solid. Increasing penetrant-matrix attraction strength reduces penetrant diffusivity due to physical bonding. For size ratios approaching unity, a distinct dynamical regime emerges associated with strong slaving of penetrant hopping to matrix structural relaxation. A crossover regime at intermediate penetrant-matrix size ratio connects the two limiting behaviors for hard penetrants, but essentially disappears if there are strong attractions with the matrix. Activated penetrant diffusivity decreases strongly with matrix volume fraction in a manner that intensifies as the size ratio increases. We propose and implement a quasi-universal approach for activated diffusion of a rigid atomic/molecular penetrant in a supercooled liquid based on a mapping between the hard sphere system and thermal liquids. Calculations for specific systems agree reasonably well with experiments over a wide range of temperature, covering more than 10 orders of magnitude of variation of the penetrant diffusion constant.
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Affiliation(s)
- Rui Zhang
- Department of Materials Science and Frederick Seitz Materials Research Laboratory, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801, USA
| | - Kenneth S Schweizer
- Department of Materials Science and Frederick Seitz Materials Research Laboratory, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801, USA
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Filibian M, Colombo Serra S, Moscardini M, Rosso A, Tedoldi F, Carretta P. The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid. Phys Chem Chem Phys 2015; 16:27025-36. [PMID: 25382595 DOI: 10.1039/c4cp02636e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The temperature dependence of (1)H and (13)C nuclear spin-lattice relaxation rate 1/T1 has been studied in the 1.6-4.2 K temperature range in pure pyruvic acid and in pyruvic acid containing trityl radicals at a concentration of 15 mM. The temperature dependence of 1/T1 is found to follow a quadratic power law for both nuclei in the two samples. Remarkably the same temperature dependence is displayed also by the electron spin-lattice relaxation rate 1/T1e in the sample containing radicals. These results are explained by considering the effect of the structural dynamics on the relaxation rates in pyruvic acid. Dynamic nuclear polarization experiments show that below 4 K the (13)C build up rate scales with 1/T1e, in analogy to (13)C 1/T1 and consistently with a thermal mixing scenario where all the electrons are collectively involved in the dynamic nuclear polarization process and the nuclear spin reservoir is in good thermal contact with the electron spin system.
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Affiliation(s)
- M Filibian
- Università degli studi di Pavia, Dipartimento di Fisica e Unità CNISM, Via Bassi, 6, Pavia, Italy.
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8
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Schmidtke B, Petzold N, Pötzschner B, Weingärtner H, Rössler EA. Relaxation Stretching, Fast Dynamics, and Activation Energy: A Comparison of Molecular and Ionic Liquids as Revealed by Depolarized Light Scattering. J Phys Chem B 2014; 118:7108-18. [DOI: 10.1021/jp412297u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- B. Schmidtke
- Experimentalphysik
II, Universität Bayreuth, D-95444 Bayreuth, Germany
| | - N. Petzold
- Experimentalphysik
II, Universität Bayreuth, D-95444 Bayreuth, Germany
| | - B. Pötzschner
- Experimentalphysik
II, Universität Bayreuth, D-95444 Bayreuth, Germany
| | - H. Weingärtner
- Physikalische
Chemie II, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - E. A. Rössler
- Experimentalphysik
II, Universität Bayreuth, D-95444 Bayreuth, Germany
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9
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Adichtchev SV, Malinovsky VK, Ignatieva LN, Merkulov EB, Surovtsev NV. Low-frequency inelastic light scattering in a ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass. J Chem Phys 2014; 140:184508. [PMID: 24832289 DOI: 10.1063/1.4875095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Low-frequency (down to 30 GHz) inelastic light scattering is studied in a multicomponent glass ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) in a wide temperature range. The contributions of the THz vibrational spectrum (boson peak) and of the fast relaxation are extracted and analyzed. It is shown that the fast relaxation spectrum is described by a distribution of relaxation times leading to a power-law ν(α) dependence in the frequency range 30-300 GHz. Temperature dependence of α(T) is well described by the Gilroy-Phillips model, while the integrated intensity of the fast relaxation increases significantly with the temperature. This feature distinguishes the fast relaxation in ZBLAN from the case of most single-component glasses. Thermodynamic and kinetic fragility indexes are significantly different for the ZBLAN glass. The correlations between the boson peak intensity, elastic moduli, and fragility index, found earlier for single-component glasses, are fulfilled for the thermodynamic fragility index of ZBLAN. In contrast, the correlation between the fast relaxation intensity at Tg and the fragility holds better for the kinetic fragility index of ZBLAN. We propose that thermodynamic and kinetic fragilities reflect different aspects of glassy dynamics in the case of glass formers with the complex chemical composition and structure topology: the former correlates with the elastic properties and the boson peak, the latter with the relaxation.
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Affiliation(s)
- S V Adichtchev
- Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - V K Malinovsky
- Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - L N Ignatieva
- Institute of Chemistry, Far East Branch of Russian Academy of Sciences, Vladivostok 690022, Russia
| | - E B Merkulov
- Institute of Chemistry, Far East Branch of Russian Academy of Sciences, Vladivostok 690022, Russia
| | - N V Surovtsev
- Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
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10
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Schmidtke B, Petzold N, Kahlau R, Rössler EA. Reorientational dynamics in molecular liquids as revealed by dynamic light scattering: From boiling point to glass transition temperature. J Chem Phys 2013; 139:084504. [DOI: 10.1063/1.4817406] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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11
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Tanaka H. Bond orientational order in liquids: Towards a unified description of water-like anomalies, liquid-liquid transition, glass transition, and crystallization: Bond orientational order in liquids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:113. [PMID: 23104614 DOI: 10.1140/epje/i2012-12113-y] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 09/28/2012] [Indexed: 06/01/2023]
Abstract
There are at least three fundamental states of matter, depending upon temperature and pressure: gas, liquid, and solid (crystal). These states are separated by first-order phase transitions between them. In both gas and liquid phases a complete translational and rotational symmetry exist, whereas in a solid phase both symmetries are broken. In intermediate phases between liquid and solid, which include liquid crystal and plastic crystal phases, only one of the two symmetries is preserved. Among the fundamental states of matter, the liquid state is the most poorly understood. We argue that it is crucial for a better understanding of liquids to recognize that a liquid generally has the tendency to have a local structural order and its presence is intrinsic and universal to any liquid. Such structural ordering is a consequence of many-body correlations, more specifically, bond angle correlations, which we believe are crucial for the description of the liquid state. We show that this physical picture may naturally explain difficult unsolved problems associated with the liquid state, such as anomalies of water-type liquids (water, Si, Ge, ...), liquid-liquid transition, liquid-glass transition, crystallization and quasicrystal formation, in a unified manner. In other words, we need a new order parameter representing a low local free-energy configuration, which is a bond orientational order parameter in many cases, in addition to a density order parameter for the physical description of these phenomena. Here we review our two-order-parameter model of liquid and consider how transient local structural ordering is linked to all of the above-mentioned phenomena. The relationship between these phenomena is also discussed.
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Affiliation(s)
- Hajime Tanaka
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505, Tokyo, Japan.
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12
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Demmel F, Morkel C. Nonexponential relaxation in a simple liquid metal. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:051204. [PMID: 23004742 DOI: 10.1103/physreve.85.051204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Indexed: 06/01/2023]
Abstract
A hallmark of the changes in dynamics towards the glass transition is the stretched exponential structural relaxation. Quasielastic neutron scattering results on liquid rubidium demonstrate such a nonexponential relaxation process in a simple liquid metal above the melting point. The nonexponential decay is an indication of non-Markovian dynamics and points to the collective character of the relaxation process. Describing the relaxation dynamics by a two-step process, the long lasting part of the decay process is in remarkable quantitative agreement with predictions from mode coupling theory. The feedback mechanism of the slowing down process in the theoretical description suggests that this contribution is at the origin of the structural arrest. With rising temperature the intermediate scattering function transforms into a simple exponential decay at a temperature range which indicates the end of the highly viscous solidlike behavior in the liquid.
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Affiliation(s)
- F Demmel
- ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom.
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13
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Kruk D, Herrmann A, Rössler EA. Field-cycling NMR relaxometry of viscous liquids and polymers. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 63:33-64. [PMID: 22546344 DOI: 10.1016/j.pnmrs.2011.08.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 08/17/2011] [Indexed: 05/27/2023]
Affiliation(s)
- D Kruk
- Universität Bayreuth, Experimentalphysik II, 95440 Bayreuth, Germany
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14
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Schwaiger F, Zimmermann W, Köhler W. Transient cage formation around hot gold colloids dispersed in polymer solutions. J Chem Phys 2011; 135:224905. [DOI: 10.1063/1.3665935] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Popova VA, Surovtsev NV. Temperature dependence of the Landau-Placzek ratio in glass forming liquids. J Chem Phys 2011; 135:134510. [DOI: 10.1063/1.3645196] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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16
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Domschke M, Marsilius M, Blochowicz T, Voigtmann T. Glassy relaxation and excess wing in mode-coupling theory: the dynamic susceptibility of propylene carbonate above and below T(c). PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:031506. [PMID: 22060378 DOI: 10.1103/physreve.84.031506] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Indexed: 05/31/2023]
Abstract
We explore the possibility of describing experimental susceptibility spectra of the glass former propylene carbonate with a two-component schematic model of mode-coupling theory (MCT) from above the melting point down to temperatures far below the critical temperature of MCT. By introducing a phenomenological time-dependent hopping rate, the spectra are reproduced in the full frequency and temperature range available. Literature data of dielectric susceptibilities and depolarized Brillouin light-scattering spectra are combined with our measurements of photon correlation spectroscopy to cover up to 18 decades in frequency of spectra for two different dynamical variables. A consistent description of all data sets is obtained by adjusting only a few physically motivated parameters. In particular the excess wing or slow β-relaxation commonly observed in the susceptibility spectra can consistently be modeled as originating from a coupling of the individual experimental probe correlator to the collective density fluctuations.
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Affiliation(s)
- Markus Domschke
- Institut für Festkörperphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
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17
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Michels JJ. Surface-Directed Spinodal Decomposition of Solvent-Quenched Organic Transistor Blends. Chemphyschem 2010; 12:342-8. [DOI: 10.1002/cphc.201000873] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Indexed: 11/12/2022]
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18
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Petzold N, Rössler EA. Light scattering study on the glass former o-terphenyl. J Chem Phys 2010; 133:124512. [DOI: 10.1063/1.3478533] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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19
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Greenall MJ, Cates ME. Crossover behavior and multistep relaxation in a schematic model of the cut-off glass transition. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:051503. [PMID: 17677069 DOI: 10.1103/physreve.75.051503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Indexed: 05/16/2023]
Abstract
We study a schematic mode-coupling model in which the ideal glass transition is cut off by a decay of the quadratic coupling constant in the memory function. (Such a decay, on a time scale tau I , has been suggested as the likely consequence of activated processes.) If this decay is complete, so that only a linear coupling remains at late times, then the alpha relaxation shows a temporal crossover from a relaxation typical of the unmodified schematic model to a final strongly slower-than-exponential relaxation. This crossover, which differs somewhat in form from previous schematic models of the cutoff glass transition, resembles light-scattering experiments on colloidal systems, and can exhibit a "slower-than- alpha " relaxation feature hinted at there. We also consider what happens when a similar but incomplete decay occurs, so that a significant level of quadratic coupling remains for t>>tau I . In this case the correlator acquires a third, weaker relaxation mode at intermediate times. This empirically resembles the beta process seen in many molecular glass formers. It disappears when the initial as well as the final quadratic coupling lies on the liquid side of the glass transition, but remains present even when the final coupling is only just inside the liquid (so that the alpha relaxation time is finite, but too long to measure). Our results are suggestive of how, in a cutoff glass, the underlying "ideal" glass transition predicted by mode-coupling theory can remain detectable through qualitative features in dynamics.
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Affiliation(s)
- M J Greenall
- SUPA, School of Physics, University of Edinburgh, JCMB King's Buildings, Edinburgh, UK
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22
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Brodin A, Rössler EA. Depolarized light scattering versus optical Kerr effect spectroscopy of supercooled liquids: Comparative analysis. J Chem Phys 2006; 125:114502. [PMID: 16999485 DOI: 10.1063/1.2336782] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recently, heterodyne-detected optical Kerr effect (HD-OKE) spectroscopy was used to study dynamics of supercooled molecular liquids. The studies revealed an apparently new physical phenomenon that had not been reported before from the related depolarized light scattering (DLS), namely, an intermediate power law (nearly logarithmic decay) of the response functions [H. Cang et al., J. Chem. Phys. 118, 2800 (2003)]. Conceptually, HD-OKE and DLS data reflect optical anisotropy fluctuations mainly due to molecular reorientation dynamics in time and frequency domains, respectively. The above-mentioned effects are revealed in the mesoscopic range less, similar1 GHz ( greater, similar100 ps), where no direct comparison of the techniques was reported. In this Communication, we attempt such a comparison of exemplifying HD-OKE literature data of the glass-forming salol (phenyl salicylate), benzophenone, and liquid-crystal forming 4-cyano-4(')-pentylbiphenyl with DLS data of the same systems that we measured down to ca. 200 MHz by a combined tandem Fabry-Perot interferometer plus tandem-grating-monochromator technique. Generally, we find a satisfactory agreement, albeit in some cases with subtle differences at frequencies greater, similar10 GHz. We conclude that, in the mesoscopic dynamic range, HD-OKE and DLS studies provide consistent and comparable information, and therefore their conclusions must agree. We argue that the intermediate power law of HD-OKE is in essence a manifestation of the excess wing of the corresponding frequency-domain data, known long since from broadband dielectric spectroscopy and anticipated from DLS studies of supercooled liquids.
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Affiliation(s)
- Alexander Brodin
- Experimentalphysik II, Universität Bayreuth, D-95440 Bayreuth, Germany.
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Li J, Wang I, Fruchey K, Fayer MD. Dynamics in Supercooled Ionic Organic Liquids and Mode Coupling Theory Analysis. J Phys Chem A 2006; 110:10384-91. [PMID: 16942043 DOI: 10.1021/jp0637476] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Optically heterodyne-detected optical Kerr effect experiments are applied to study the orientational dynamics of the supercooled ionic organic liquids N-propyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide (PMPIm) and 1-ethyl-3-methylimidazolium tosylate (EMImTOS). The orientational dynamics are complex with relaxation involving several power law decays followed by a final exponential decay. A mode coupling theory (MCT) schematic model, the Sjögren model, was able to reproduce the PMPIm data very successfully over a wide range of times from 1 ps to hundreds of ns for all temperatures studied. Over the temperature range from room temperature down to the critical temperature Tc of 231 K, the OHD-OKE signal of PMPIm is characterized by the intermediate power law t(-1.00+/-0.04) at short times, a von Schweidler power law t(-0.51+/-0.03) at intermediate times, and a highly temperature-dependent exponential (alpha relaxation) at long times. This form of the decay is identical to the form observed previously for a large number of organic van der Waals liquids. MCT analysis indicates that the theory can explain the experimental data very well for a range of temperatures above Tc, but as might be expected, there are some deviations from the theoretical modeling at temperatures close to Tc. For EMImTOS, the orientational dynamics were studied on the ps time scale in the deeply supercooled region near its glass transition temperature. The orientational relaxation of EMImTOS clearly displays the feature associated with the boson peak at approximately 2 ps, which is the first time domain evidence of the boson peak in ionic organic liquids. Overall, all the dynamical features observed earlier for organic van der Waals liquids using the same experimental technique are also observed for organic ionic liquids.
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Affiliation(s)
- Jie Li
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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24
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Sperl M. Cole-Cole law for critical dynamics in glass-forming liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:011503. [PMID: 16907096 DOI: 10.1103/physreve.74.011503] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2006] [Indexed: 05/11/2023]
Abstract
Within the mode-coupling theory (MCT) for glassy dynamics, the asymptotic low-frequency expansions for the dynamical susceptibilities at critical points are compared to the expansions for the dynamic moduli; this shows that the convergence properties of the two expansions can be quite different. In some parameter regions, the leading-order expansion formula for the modulus describes the solutions of the MCT equations of motion outside the transient regime successfully; at the same time, the leading- and next-to-leading-order expansion formulas for the susceptibility fail. In these cases, one can derive a Cole-Cole law for the susceptibilities; and this law accounts for the dynamics for frequencies below the band of microscopic excitations and above the high-frequency part of the alpha peak. It is shown that this scenario explains the optical-Kerr-effect data measured for salol and benzophenone (BZP). For BZP it is inferred that the depolarized light-scattering spectra exhibit a wing for the alpha peak within the Gigahertz band. This wing results from the crossover of the von Schweidler law part of the alpha peak to the high-frequency part of the Cole-Cole peak; and this crossover can be described quantitatively by the leading-order formulas of MCT for the modulus.
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Affiliation(s)
- Matthias Sperl
- Department of Physics, Duke University, Box 90305, Durham, North Carolina 27708, USA
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25
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Vainer YG, Naumov AV, Bauer M, Kador L. Dispersion of the local parameters of quasilocalized low-frequency vibrational modes in a low-temperature glass: Direct observation via single-molecule spectroscopy. J Chem Phys 2005; 122:244705. [PMID: 16035791 DOI: 10.1063/1.1929736] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Spectra of single tetra-tert-butylterrylene chromophore molecules embedded in an amorphous polyisobutylene matrix as microprobes were recorded. The individual temperature dependences of the spectral linewidths for the same single molecules (SMs) in a broad temperature interval (1.6 < T < 40 K) have been measured. This enabled us to separate the contributions of tunneling two-level systems and quasilocalized low-frequency vibrational modes (LFMs) to the observed linewidths. The analysis of the T dependences yields the values of LFM frequencies and SM-LFM coupling constants for the LFMs in the local environment of a given chromophore. Pronounced distributions of the observed parameters of LFMs were found. This result can be regarded as the first direct experimental proof of the localized nature of LFMs in glasses.
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Affiliation(s)
- Yuri G Vainer
- Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow Region.
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26
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Rauch J, Köhler W. On the Molar Mass Dependence of the Thermal Diffusion Coefficient of Polymer Solutions. Macromolecules 2005. [DOI: 10.1021/ma050231w] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. Rauch
- Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - W. Köhler
- Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
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27
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Weiss EA, Tauber MJ, Ratner MA, Wasielewski MR. Electron Spin Dynamics as a Probe of Molecular Dynamics: Temperature-Dependent Magnetic Field Effects on Charge Recombination within a Covalent Radical Ion Pair. J Am Chem Soc 2005; 127:6052-61. [PMID: 15839706 DOI: 10.1021/ja043398y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The electron spin-spin exchange interaction, 2J, in radical pairs (RPs) is exquisitely sensitive to the details of molecular structure and can thus serve as an important probe of structural dynamics in RPs of potential interest to photonic and electronic devices. Photoinitiated ultrafast two-step charge separation produces (1)(MeOAn(+)(*)-6ANI-NI(-)(*)), where MeOAn = p-methoxyaniline, 6ANI = 4-(N-piperidinyl)naphthalene-1,8-dicarboximide, and NI = naphthalene-1,8:4,5-bis(dicarboximide). Radical pair intersystem crossing subsequently produces (3)(MeOAn(+)(*)-6ANI-NI(-)(*)), and the total RP population decays with approximately 10 ns lifetime at 140 K, which increases to nearly 30 ns at 300 K in toluene. The activation energy observed for this process is negative and can be explained by a mechanism involving a conformational preequilibrium of the RP followed by charge recombination. Over the same temperature range, the magnetic field effect (MFE) on yield of the triplet recombination product, MeOAn-6ANI-(3)()NI, yields the magnitude of 2J, which directly monitors the superexchange electronic coupling for charge recombination. A single resonance in the MFE plot is observed at 300 K, which splits into two resonances at temperatures below 230 K, suggesting that there are two distinct groups of RP conformations at low temperature. The magnitude of 2J for the lower field resonance (10 mT) at 140 K is 5 times smaller than that of the high field resonance. At 300 K the equilibrium is shifted almost entirely to the set of conformers with the stronger electronic coupling. The motion that couples these two groups of conformations is the motion that most effectively gates the donor-acceptor electronic coupling.
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Affiliation(s)
- Emily A Weiss
- Center for Nanofabrication and Molecular Self-Assembly and Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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28
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Zelent B, Nucci NV, Vanderkooi JM. Liquid and Ice Water and Glycerol/Water Glasses Compared by Infrared Spectroscopy from 295 to 12 K. J Phys Chem A 2004. [DOI: 10.1021/jp0475584] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bogumil Zelent
- Johnson Research Foundation, Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
| | - Nathaniel V. Nucci
- Johnson Research Foundation, Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
| | - Jane M. Vanderkooi
- Johnson Research Foundation, Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
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29
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Watanabe J, Tohji M, Ohtsuka E, Miyake Y, Kinoshita S. Direct comparison of the temperature dependence of the response functions measured by light scattering and optical Kerr effect spectroscopy. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.07.100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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30
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Zhang HP, Brodin A, Barshilia HC, Shen GQ, Cummins HZ, Pick RM. Brillouin scattering study of salol: exploring the effects of rotation-translation coupling. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 70:011502. [PMID: 15324051 DOI: 10.1103/physreve.70.011502] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2003] [Indexed: 05/24/2023]
Abstract
Brillouin scattering in liquids composed of optically and mechanically anisotropic molecules is affected by coupling between rotational and translational dynamics. While this effect has been extensively studied in depolarized (VH) scattering where it produces the "Rytov dip," recent theoretical analyses by Pick, Franosch show that it should also produce observable effects in polarized (VV) scattering [Eur. Phys. J. B 31, 217 (2003)]; 31, 229 (2003)]]. To test this theory, we carried out Brillouin scattering studies of the molecular glassformer salol in the temperature range 210-380 K, including VH-backscattering, VH-90 degrees, and VV-90 degrees spectra. The data were analyzed consistently to determine the effects of rotation-translation coupling on both the polarized and depolarized spectra. A previously unanticipated feature predicted by these authors was observed: a narrow negative region in the q -dependent part of the 90 degrees VV spectra, which we designate as the "VV dip." It is an analog of the Rytov dip observed at high temperatures in the 90 degrees VH spectra, which is also accurately described by this theory. Analysis of the 90 degrees VV spectra was carried out both with and without inclusion of translation-rotation coupling in order to determine quantitatively the role this coupling plays.
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Affiliation(s)
- H P Zhang
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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31
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Chumakov AI, Sergueev I, van Bürck U, Schirmacher W, Asthalter T, Rüffer R, Leupold O, Petry W. Collective nature of the boson peak and universal transboson dynamics of glasses. PHYSICAL REVIEW LETTERS 2004; 92:245508. [PMID: 15245100 DOI: 10.1103/physrevlett.92.245508] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Indexed: 05/24/2023]
Abstract
Using probe molecules with resonant nuclei and nuclear inelastic scattering, we are able to measure the density of states exclusively for collective motions with a correlation length of more than approximately 20 A. Such spectra exhibit an excess of low-energy modes (boson peak). This peak behaves in the same way as that observed by conventional methods. This shows that a significant part of the modes constituting the boson peak is of collective character. At energies above the boson peak, the reduced density of states of the collective motions universally exhibits an exponential decrease.
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Affiliation(s)
- A I Chumakov
- European Synchrotron Radiation Facility, P.O. Box 220, F-38043 Grenoble, France
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32
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Surovtsev NV, Adichtchev SV, Wiedersich J, Novikov VN, Rössler EA. Fast relaxation in the structural glass and glassy crystal of ethanol and cyano cyclohexane: A quasielastic light scattering study. J Chem Phys 2003. [DOI: 10.1063/1.1623180] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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33
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Rauch J, Köhler W. Collective and thermal diffusion in dilute, semidilute, and concentrated solutions of polystyrene in toluene. J Chem Phys 2003. [DOI: 10.1063/1.1623745] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Naumov AV, Vainer YG, Bauer M, Kador L. Dynamics of a doped polymer at temperatures where the two-level system model of glasses fails: Study by single-molecule spectroscopy. J Chem Phys 2003. [DOI: 10.1063/1.1603215] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Adichtchev S, Blochowicz T, Tschirwitz C, Novikov VN, Rössler EA. Reexamination of the evolution of the dynamic susceptibility of the glass former glycerol. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:011504. [PMID: 12935147 DOI: 10.1103/physreve.68.011504] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2002] [Indexed: 05/24/2023]
Abstract
The dielectric data of glycerol compiled by Lunkenheimer et al. [Contemp. Phys. 41, 15 (2000)] are reanalyzed within a phenomenological approach on the one hand, and within mode coupling theory (MCT), on the other. We present a complete interpolation of the dielectric data covering 17 decades in frequencies. The crossover temperature extracted from the phenomenological analysis of the slow response at low temperatures and defined by the emergence of the excess wing upon cooling agrees well with the critical temperature extracted from a MCT analysis of the dynamics at high temperatures including data that were not used in the first MCT analysis of glycerol by Lunkenheimer et al. [Phys. Rev. Lett. 77, 318 (1996)]. The crossover temperature is found to be T(c)=288+/-3 K, which is significantly higher than previously reported. Extracting the nonergodicity parameter f, the characteristic anomaly is only found when 1-f is inspected, since f is very close to 1. No difference for the evolution of the dynamic susceptibility is observed for the nonfragile system glycerol with respect to fragile glass formers provided that the evolution of the dynamics is studied as a function of the correlation time tau(alpha).
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Affiliation(s)
- S Adichtchev
- Experimentalphysik II, Universität Bayreuth, D 95440 Bayreuth, Germany
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36
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37
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Novikov VN, Sokolov AP. Universality of the dynamic crossover in glass-forming liquids: a "magic" relaxation time. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:031507. [PMID: 12689073 DOI: 10.1103/physreve.67.031507] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2002] [Revised: 12/02/2002] [Indexed: 05/24/2023]
Abstract
Analysis of experimental data on the structural relaxation time tau(alpha) in various glass formers revealed its universality at the critical temperature T(c) of the mode-coupling theory. In most glass formers studied ln tau(alpha)(T(c))=-(6.5-7.5). Possible reasons for such a universality are discussed.
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Affiliation(s)
- V N Novikov
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, USA
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38
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39
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Blochowicz T, Tschirwitz C, Benkhof S, Rössler EA. Susceptibility functions for slow relaxation processes in supercooled liquids and the search for universal relaxation patterns. J Chem Phys 2003. [DOI: 10.1063/1.1563247] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Prevosto D, Bartolini P, Torre R, Ricci M, Taschin A, Capaccioli S, Lucchesi M, Rolla P. Relaxation processes in an epoxy resin studied by time-resolved optical Kerr effect. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 66:011502. [PMID: 12241365 DOI: 10.1103/physreve.66.011502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2002] [Indexed: 05/23/2023]
Abstract
The dynamics of the epoxy resin phenyl glycidyl ether, a fragile glass-forming liquid, is investigated in the liquid and supercooled phases by time-resolved optical Kerr effect experiment with an heterodyne detection technique. We tested the mode-coupling theory and found that the predicted dynamic scenario allows to reproduce properly the measured signal, for t>1 ps, in the whole temperature interval investigated. Furthermore, the values of T(c) and lambda, obtained from the analysis of three different and independent dynamic regimes (alpha regime, von Schweidler, beta regime), are in remarkable agreement. Moreover, relaxation times obtained from optical Kerr effect and dielectric spectroscopy measurements are compared. The two time scales differ only for a constant factor in the whole temperature interval investigated.
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Affiliation(s)
- D Prevosto
- Dipartimento di Fisica, Università di Pisa, and INFM, via F. Buonarroti 2, I-56127, Pisa, Italy
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41
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Vainer YG, Kol’chenko MA, Naumov AV, Personov RI, Zilker SJ, Haarer D. Optical dephasing in doped organic glasses over a wide (0.35–100 K) temperature range: Solid toluene doped with Zn–octaethylporphine. J Chem Phys 2002. [DOI: 10.1063/1.1473196] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Rauch J, Köhler W. Diffusion and thermal diffusion of semidilute to concentrated solutions of polystyrene in toluene in the vicinity of the glass transition. PHYSICAL REVIEW LETTERS 2002; 88:185901. [PMID: 12005700 DOI: 10.1103/physrevlett.88.185901] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2001] [Indexed: 05/23/2023]
Abstract
The approaching glass transition in polystyrene/toluene solutions leads to a sharp decay of both the collective diffusion coefficient D and the thermal diffusion coefficient D(T) at concentrations above 0.2 g/cm(3). The Soret coefficient S(T) = D(T)/D follows power-law scaling from semidilute to concentrated and is not influenced by the slowing down of the dynamics associated with the glass transition. Both D and D(T) are governed by the same friction coefficient. The scaling behavior of S(T) with concentration on approach of the glass transition is compared to the divergence of S(T) near a consolute critical point.
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Affiliation(s)
- J Rauch
- Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
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43
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Brodin A, Frank M, Wiebel S, Shen G, Wuttke J, Cummins HZ. Brillouin-scattering study of propylene carbonate: an evaluation of phenomenological and mode coupling analyses. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:051503. [PMID: 12059560 DOI: 10.1103/physreve.65.051503] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2001] [Indexed: 05/23/2023]
Abstract
Brillouin-scattering spectra of the molecular glass-forming material propylene carbonate (PC) in the temperature range 140 K to 350 K were analyzed using both the phenomenological Cole-Davidson memory function and a hybrid memory function consisting of the Cole-Davidson function plus a power-law term representing the critical decay part of the fast beta relaxation. The spectra were also analyzed using the extended two-correlator schematic mode-coupling theory (MCT) model recently employed by Götze and Voigtmann to analyze depolarized light backscattering, dielectric, and neutron-scattering spectra of PC [Phys. Rev. E 61, 4133 (2000)]. We assess the ability of the phenomenological and MCT fits, each with three free fitting parameters, to simultaneously describe the spectra and give reasonable values for the alpha-relaxation time tau(alpha).
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Affiliation(s)
- Alexander Brodin
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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44
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Chong SH, Götze W. Idealized glass transitions for a system of dumbbell molecules. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:041503. [PMID: 12005825 DOI: 10.1103/physreve.65.041503] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2001] [Indexed: 05/23/2023]
Abstract
The mode-coupling theory for ideal glass transitions in simple systems is generalized to a theory for the glassy dynamics of molecular liquids using the density fluctuations of the sites of the molecule's constituent atoms as the basic structure variables. The theory is applied to calculate the liquid-glass phase diagram and the form factors for the arrested structure of a system of symmetric dumbbells of fused hard spheres. The static structure factors, which enter the equations of motion as input, are calculated as function of the packing fraction phi and the molecule's elongation zeta within the reference-interaction-site-model and Percus-Yevick theories. The critical packing fraction phi(c) for the glass transition is obtained as nonmonotone function of zeta with a maximum near zeta=0.43. A transition line is calculated separating a small-zeta-glass phase with ergodic dipole motion from a large-zeta-glass phase where also the reorientational motion is arrested. The Debye-Waller factors at the transition are found to be somewhat larger for sufficiently elongated systems than those for the simple hard-sphere system, but the wave-number dependence of the glass-form factors is quite similar. The dipole reorientations for zeta> or =0.6 are arrested as strongly as density fluctuations with wave vectors at the position of the first sharp diffraction peak.
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Affiliation(s)
- S-H Chong
- Physik Department, Technische Universität München, 85747 Garching, Germany
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45
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Adichtchev SV, Benkhof S, Blochowicz T, Novikov VN, Rössler E, Tschirwitz C, Wiedersich J. Anomaly of the nonergodicity parameter and crossover to white noise in the fast relaxation spectrum of a simple glass former. PHYSICAL REVIEW LETTERS 2002; 88:055703. [PMID: 11863750 DOI: 10.1103/physrevlett.88.055703] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2001] [Indexed: 05/23/2023]
Abstract
We present quasielastic light scattering and dielectric spectra of the glass former alpha-picoline. At high temperatures the evolution of the susceptibility minimum is well described by the mode coupling theory (MCT). Below the critical temperature T(c) the simple scaling laws of MCT fail due to the appearance of the excess wing of the alpha process, which shows a universal evolution as a function of log(10)tau(alpha). Taking this into account, however, we observe the predicted cusplike anomaly of the nonergodicity parameter as well as a crossover to "white noise."
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Affiliation(s)
- S V Adichtchev
- Physikalisches Institut EP II, Universität Bayreuth, 95440 Bayreuth, Germany
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