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  • 1
    Electronic Resource
    Electronic Resource
    Enthalpy relaxation of glassy water (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 809-810 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458386
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  • 2
    Electronic Resource
    Electronic Resource
    Isotope effect on the glass transition and crystallization of hyperquenched glassy water (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6742-6746 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The thermal behavior of hyperquenched glassy D2O was investigated by differential scanning calorimetry from 103 to 250 K, in order to investigate the isotope effect on the glass→liquid transition and on the liquid to cubic, and cubic to hexagonal ice. For a heating rate of 30 K min−1 the temperatures of the thermal effects are: 137 K for the onset of the reversible glass→liquid transition (Tg), 154 and 173 K for the beginning and the peak minimum of the crystallization exotherm, and ≈229 K for the peak minimum of the transformation cubic→hexagonal ice. Increase in heat capacity at Tg and the width of the glass transition are similar to those reported for glassy H2O. Tg of D2O is higher than that of H2O by an amount that is expected for isorelaxational and/or isoviscous states assuming that the functional form of the molecular reorientation rates with temperature is unaffected by the isotopic substitution. The increase in the temperature of crystallization of "fluid'' D2O is ≈three times greater than the increase in the glass→liquid transition which causes Tg and devitrification to become more separated in D2O than in H2O. Implications of these results for both the inferred λ-type anomally at ≈228 K in H2O and at ≈233 K in D2O, and the presumed formation of a gel-like structure at these temperatures are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458593
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  • 3
    Electronic Resource
    Electronic Resource
    Localized relaxation's strength and its mimicry of glass-softening thermodynamics (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 5908-5909 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dielectric relaxation strength of the β process, Δcursive-epsilonβ, in a rigid-molecular glass of 16.6 mol % chlorobenzene cis-decalin mixture increases slowly with temperature, T, until the glass-softening range is reached, and thereafter it increases rapidly, i.e., (dΔcursive-epsilonβ/dT) increases at Tg relatively abruptly. This is remarkably similar to the volume and entropy against T plots of a glass being heated through its Tg and of the implied rise in the expansion coefficient and heat capacity near Tg. The β-relaxation rate increases smoothly through Tg according to the Arrhenius equation, and the distribution of relaxation times becomes narrower. Both the entropy and free volume affect Δcursive-epsilonβ, but not the rate. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1456030
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  • 4
    Electronic Resource
    Electronic Resource
    The dielectric relaxation time of ice V, its partial anti-ferroelectric ordering and the role of Bjerrum defects (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 3274-3280 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dielectric relaxation spectra of ice V has been studied over the 133–270 K range, at frequencies in the 0.05 Hz–300 kHz range. Its dielectric relaxation time, τ, is 1.5 s at 133 K. The Arrhenius plot of its τ is found to bend sharply at ∼200 K, and the Arrhenius energy decreases from 49.9 kJ/mol at 260 K to 23.3 kJ/mol at 160 K. This confirms the inference from the orientational ordering studies that τ of ice V at 125 K is much less than 100 s [J. Chem. Phys. 112, 7169 (2000)]. The increase in the equilibrium permittivity on cooling ice V from 266 to 133 K is 77% of that anticipated from a decrease in its volume and thermal energy. The discrepancy is attributed to a gradual increase in orientational ordering of water molecules in its structure, leading to a partially antiferroelectric state at low temperatures. A comparison made with the earlier studies of uncontaminated (H2O and D2O) ice Ih and N2- and CO2-contaminated (H2O) ice Ih (impurities in the latter used to generate extrinsic Bjerrum defects), showed that the decrease in the Arrhenius energy on cooling ice V may be explained without invoking a change in mechanism from Bjerrum defects diffusion to ionic defects diffusion with zero activation energy. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1386903
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  • 5
    Electronic Resource
    Electronic Resource
    Erratum: "An estimate for the Gibbs energy of amorphous solid waters and differences between the low-density amorph and glassy water" [J. Chem. Phys. 112, 8573 (2000)] (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 10412-10412 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1322366
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  • 6
    Electronic Resource
    Electronic Resource
    An equilibrium supercooled liquid's entropy and enthalpy in the Kauzmann and the third law extrapolations, and a proposed experimental resolution (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 751-761 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In our current discussion of the thermodynamics and molecular kinetics of glass-forming liquids, the entropy is extrapolated below a liquid's vitrification temperature Tg along a curve of progressively increasing slope until a temperature Tk is reached. Here the entropy and heat capacity, Cp, of the equilibrium liquid become equal to those of its crystal. Several observations have indicated fundamental difficulties with this extrapolation, thus suggesting the need for an alternative. We propose one alternative, in which Cp of an equilibrium liquid decreases along a sigmoid-shape path stretched over a broad temperature range from above Tg to 0 K. Its entropy and Cp become equal to those of its crystal at 0 K, as required by the third law of thermodynamics, and the enthalpy and volume remain higher. To elaborate, the available Cp data of 12 supercooled liquids have been interpolated between T〉Tg and 0 K, and the enthalpy of their equilibrium state at 0 K, as well as the Gibbs free energy and enthalpy at T〈Tg, determined. The enthalpy of the equilibrium liquid state at 0 K is 17%–37% of the enthalpy of melting, and for eight out of 12 liquids the Kauzmann extrapolation and our interpolation yield values within 5% of the average. Relative merits of the two resolutions of the entropy situation may be tested by the heat of solution, enthalpy loss and vapor pressure measurements of aged nonionic glasses and emf measurement of ionic glasses forming a half-cell of an electrochemical equilibrium. The anticipated enthalpy, Gibbs energy and vapor pressure change for the Kauzmann extrapolation of Cp and our interpolation are given at T〈Tg for triphenylethene. As the equipment time needed for such measurements is only a few hours, such experiments may allow a study of the time-dependent thermodynamics of a glass more conveniently than other experiments. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481850
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  • 7
    Electronic Resource
    Electronic Resource
    An estimate for the Gibbs energy of amorphous solid waters and differences between the low-density amorph and glassy water (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8573-8580 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molar volume and compressibility of the high density amorph (HDA) and of hexagonal ice (ice Ih) were measured at 77 K and high pressures, and the Gibbs energy, G, of HDA and of the low density amorph (LDA) calculated from their volume–pressure integrals. The relative magnitudes of their G predict that a step increase from ∼3 to ∼7 kbar will transform LDA at 77 K to ice Ih, not to HDA. The excess G of LDA over ice Ih is 1.6±0.1 kJ mol−1, which is higher than the experimentally determined value of 1.1±0.1 kJ mol−1 for amorphous solid water [J. Chem. Phys. 105, 240 (1996)]. A path for the volume in the pressure plane needed to satisfy the requirement of 1.1±0.1 kJ mol−1 was not found. These suggest that LDA is different from the amorphous solid or glassy water, which is consistent with the findings by other methods, thus calling into question the inferences [Nature (London) 392, 164 (1998)] based on a thermodynamic continuity between LDA and supercooled water. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481481
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  • 8
    Electronic Resource
    Electronic Resource
    Amorphous solid water's isotopic exchange kinetics (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 2782-2789 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The mechanism for isotopic exchange by proton hopping and subsequent reorientation of H2O molecules in vapor-deposited, 0.1 mol % 2-naphthol containing amorphous solid water [M. Fischer and J. P. Devlin, J. Phys. Chem. 99, 11584 (1995)] has been reconsidered and an alternative mechanism in terms of diffusion controlled reactions is proposed. In this mechanism, H2O molecules diffuse within the H-bonded clusters, with or without a net increase in the number of H bonds, and isotopic exchange occurs by two processes: (i) Random diffusion of molecules in two clusters, one containing D2O and the other H3O+, leads to formation of an intercluster H bond, which in turn provides a path for proton hopping and converts one D2O (plus one H2O) to two coupled HODs by proton translocation and subsequent orientation. (ii) One H bond between two HOD neighbors in a cluster breaks and reforms with another H2O in the same cluster or in a different cluster, and hence a coupled HOD is converted to an uncoupled HOD. The decrease in D2O and the increase in HOD concentrations with time follow a stretched exponential kinetics, with exponent of 0.65 for the former and 0.54 for the latter process at 122 K. This is equivalent to the time-dependent rate constant in Plonka's formalism [J. Chem. Phys. 96, 1128 (1992)] and is seen as characteristic of dispersive kinetics. Because fluctuation of the environment is slower than the time scale of overall barrier crossing, the mass-controlled kinetics equations do not apply to a consecutive reaction scheme. The known variation of the isotopic species concentration with time seems to be consistent with this reaction kinetics. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1490593
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  • 9
    Electronic Resource
    Electronic Resource
    The entropy loss on supercooling a liquid and anharmonic contributions (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 2043-2046 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Interdependence of the configurational, vibrational, and anharmonic-force contributions to the entropy of a liquid during its supercooling is investigated, and the effect of the anharmonic-force contribution to the entropy at constant pressure and constant volume conditions is analyzed. For realistic values of the Grüneisen parameter and expansion coefficient of a liquid, this contribution is found to be 30–40% of the heat capacity, which is high enough to affect the relation between the viscosity and excess entropy. An analysis of the resolved contributions to entropy of liquid selenium, an N-type liquid, shows that its configurational entropy is not proportional to its excess entropy. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1431586
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of induced steric hindrance on the dielectric behavior and H bonding in the supercooled liquid and vitreous alcohol (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 4634-4642 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The extent of H bonding in alcohols may be reduced by sterically hindering its OH group. This technique is used here for investigating the reasons for the prominent Debye-type dielectric relaxation observed in monohydroxy alcohols [Kudlik et al., Europhys. Lett. 40, 549 (1997); Hansen et al., J. Chem. Phys. 107, 1086 (1997); Kalinovskaya and Vij, ibid. 112, 3262 (2000)], and broadband dielectric spectroscopy of supercooled liquid and glassy states of 1-phenyl-1-propanol is performed over the 165–238 K range. In its molecule, the steric hindrance from the phenyl group and the existence of optical isomers reduce the extent of intermolecular H bonding. The equilibrium permittivity data show that H-bonded chains do not form in the supercooled liquid, and the total polarization decays by three discrete relaxation processes, of which only the slower two could be resolved. The first is described by the Cole–Davidson-type distribution of relaxation times and a Vogel–Fulcher–Tammann-type temperature dependence of its average rate, which are characteristics of the α-relaxation process as in molecular liquids. The second is described by a Havriliak–Negami-type equation, and an Arrhenius temperature dependence, which are the characteristics of the Johari–Goldstein process of localized molecular motions. The relaxation rate's non-Arrhenius temperature dependence has been examined qualitatively in terms of the Dyre theory, which considers that the apparent Arrhenius energy itself is temperature dependent, as in the classical interpretations, and quantitatively in terms of the cooperatively rearranging region's size, without implying that there is an underlying thermodynamic transition in its equilibrium liquid. The relaxation rate also fits the power law with the critical exponent of 13.4, instead of 2–4, required by the mode-coupling theory, thereby indicating the ambiguity of the power-law equations. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1346635
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