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Koperwas K, Gapiński J, Wojnarowska Z, Patkowski A, Paluch M. Experimental examination of dipole-dipole cross-correlations by dielectric spectroscopy, depolarized dynamic light scattering, and computer simulations of molecular dynamics. Phys Rev E 2024; 109:034608. [PMID: 38632762 DOI: 10.1103/physreve.109.034608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 02/15/2024] [Indexed: 04/19/2024]
Abstract
The contribution of cross- and self-correlations to the dielectric and light-scattering spectra of supercooled polar glass formers has recently become a most challenging problem. Herein, we employ dielectric spectroscopy, depolarized dynamic light scattering (DDLS), and rheology to thoroughly examine the dynamics of van der Waals liquid 1,2-Diphenylvinylene. Carbonate (DVC), which is a polar counterpart of canonical glass former ortho-Terphenyl (OTP). We show that the light-scattering data correspond well with the dielectric permittivity function over a wide T range. This pattern is very different from the peaks' separation ω_{max}^{DDLS}/ω_{max}^{BDS}=3.7 reported recently for tributyl phosphate (TBP), despite the same dielectric characteristics of these two glass formers (β_{KWW}=0.75, Δɛ=20 for both TBP and DVC; KWW stands for Kohlrausch-Williams-Watts). This indicates different influence of orientational correlations in both methods for these two systems. We also show the results of the computer simulations of the model, polar molecules, which clearly indicate that the contribution of the cross-term to the correlation function probed in the DDLS experiment can be significant.
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Affiliation(s)
- K Koperwas
- Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzow, Poland
| | - J Gapiński
- Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
| | - Z Wojnarowska
- Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzow, Poland
| | - A Patkowski
- Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
| | - M Paluch
- Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzow, Poland
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Pabst F, Blochowicz T. On the intensity of light scattered by molecular liquids-Comparison of experiment and quantum chemical calculations. J Chem Phys 2022; 157:244501. [PMID: 36586992 DOI: 10.1063/5.0133511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The intensity of light scattered by liquids has been studied for over a century since the valuable microscopic information about the molecules can be obtained, such as the anisotropy of the molecular polarizability tensor or preferred orientations of neighboring molecules. However, in modern dynamic light scattering experiments, the scattering intensity is usually disregarded, unlike in dielectric spectroscopy, which can be considered as a complementary experimental method, where the dielectric strength is routinely evaluated. The reason lies partly on the fact that the exact form of the equations relating the macroscopically measured light scattering intensity to the microscopic properties of the molecules is debated in the literature. Therefore, as a first step, we compare anisotropy parameters from the literature, calculated from light scattering intensities using different equations, with quantum chemical calculations for over 150 medium-sized molecules. This allows us to identify a consistent form of equations. In a second part, we turn to the depolarized light scattering spectra of 13 van der Waals liquids and some mixtures thereof, recorded with a combination of Tandem-Fabry-Perót and Raman spectroscopies, giving direct access to the reorientational dynamics of the molecules. We discuss how the strength of the structural α-relaxation is connected to the anisotropy parameter, what implication this has for the shape of the α-relaxation, how the components of a mixture-also for the case of ionic liquids-can be identified in this way, and how orientational correlation parameters can be extracted. Additionally, we point out for the example of n-alkanes that for highly flexible molecules, the reorientational motion might not be the decisive source of the depolarized scattered light. We also show that light scattering might serve as a sensitive tool to check the accuracy of a conformer ensemble obtained by quantum chemical calculations.
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Affiliation(s)
- Florian Pabst
- TU Darmstadt, Institute of Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Thomas Blochowicz
- TU Darmstadt, Institute of Condensed Matter Physics, 64289 Darmstadt, Germany
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Becher M, Körber T, Döß A, Hinze G, Gainaru C, Böhmer R, Vogel M, Rössler EA. Nuclear Spin Relaxation in Viscous Liquids: Relaxation Stretching of Single-Particle Probes. J Phys Chem B 2021; 125:13519-13532. [PMID: 34860530 DOI: 10.1021/acs.jpcb.1c06722] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spin-lattice relaxation rates R1(ω,T), probed via high-field and field-cycling nuclear magnetic resonance (NMR), are used to test the validity of frequency-temperature superposition (FTS) for the reorientation dynamics in viscous liquids. For several liquids, FTS is found to apply so that master curves can be generated. The susceptibility spectra are highly similar to those obtained from depolarized light scattering (DLS) and reveal an excess wing. Where FTS works, two approaches are suggested to access the susceptibility: (i) a plot of deuteron R1(T) vs the spin-spin relaxation rate R2(T) and (ii) a plot of R1(T) vs an independently measured reference time τref(T). Using single-frequency scans, (i) allows one to extract the relaxation stretching as well as the NMR coupling constant. Surveying 26 data sets, we find Kohlrausch functions with exponents 0.39 < βK ≤ 0.67. Plots of the spin-spin relaxation rate R2─rescaled by the NMR coupling constant─as a function of temperature allow one to test how well site-specific NMR relaxations couple to a given reference process. Upon cooling of flexible molecule liquids, the site-specific dynamics is found to merge, suggesting that near Tg the molecules reorient essentially as a rigid entity. This presents a possible resolution for the much lower stretching parameters reported here at high temperatures that contrast with the ones that were reported to be universal in a recent DLS study close to Tg. Our analysis underlines that deuteron relaxation is a uniquely powerful tool to probe single-particle reorientation.
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Affiliation(s)
- M Becher
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Th Körber
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - A Döß
- Department Chemie, Johannes Gutenberg-Universität, 55128 Mainz, Germany
| | - G Hinze
- Department Chemie, Johannes Gutenberg-Universität, 55128 Mainz, Germany
| | - C Gainaru
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - R Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - M Vogel
- Institut für Physik kondensierter Materie, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - E A Rössler
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
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Sivokhin AР, Kazantsev OA. Temperature Dependence of the Rayleigh Ratio for Toluene: Thermoresponsive Polymers Characterization. ChemistrySelect 2021. [DOI: 10.1002/slct.202102196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Alexey Р. Sivokhin
- Department of Chemical and Food Technology Nizhny Novgorod State Technical University n.a. R.E. Alekseev 24 Minin St. Nizhny Novgorod 603950 Russia
| | - Oleg A. Kazantsev
- Department of Chemical and Food Technology Nizhny Novgorod State Technical University n.a. R.E. Alekseev 24 Minin St. Nizhny Novgorod 603950 Russia
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Körber T, Stäglich R, Gainaru C, Böhmer R, Rössler EA. Systematic differences in the relaxation stretching of polar molecular liquids probed by dielectric vs magnetic resonance and photon correlation spectroscopy. J Chem Phys 2020; 153:124510. [DOI: 10.1063/5.0022155] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Thomas Körber
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Robert Stäglich
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Catalin Gainaru
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Roland Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Ernst A. Rössler
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
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Gabriel J, Pabst F, Blochowicz T. Debye Process and β-Relaxation in 1-Propanol Probed by Dielectric Spectroscopy and Depolarized Dynamic Light Scattering. J Phys Chem B 2017; 121:8847-8853. [PMID: 28872311 DOI: 10.1021/acs.jpcb.7b06134] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We revisit the reorientational dynamics of 1-propanol as a prototype of a monohydroxy alcohol and H-bonding system by dielectric spectroscopy (DS) and depolarized dynamic light scattering (DDLS). In particular, we address the question of whether the Debye relaxation, which is seen as a dominant process in DS, is visible in light scattering and discuss how the Johari-Goldstein (JG) β-process, which is also a prominent feature of the dielectric spectrum, appears in photon correlation spectroscopy. For that purpose we performed depolarized photon correlation experiments with an improved setup and performed additional time domain dielectric experiments which gives us the possibility to compare dielectric and light scattering data in a broad temperature range. It turns out that the improved setup allows to unambiguously identify the JG β-process, which shows almost identical properties in DDLS as in the dielectric spectra, but a Debye relaxation is not present in the DDLS data and can be excluded down to a level of 2.5% of the α-process amplitude.
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Affiliation(s)
- Jan Gabriel
- Institut für Festkörperphysik, Technische Universität Darmstadt , 64289 Darmstadt, Germany
| | - Florian Pabst
- Institut für Festkörperphysik, Technische Universität Darmstadt , 64289 Darmstadt, Germany
| | - Thomas Blochowicz
- Institut für Festkörperphysik, Technische Universität Darmstadt , 64289 Darmstadt, Germany
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Bernini S, Puosi F, Leporini D. Thermodynamic scaling of relaxation: insights from anharmonic elasticity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:135101. [PMID: 28102828 DOI: 10.1088/1361-648x/aa5a7e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using molecular dynamics simulations of a molecular liquid, we investigate the thermodynamic scaling (TS) of the structural relaxation time [Formula: see text] in terms of the quantity [Formula: see text], where T and ρ are the temperature and density, respectively. The liquid does not exhibit strong virial-energy correlations. We propose a method for evaluating both the characteristic exponent [Formula: see text] and the TS master curve that uses experimentally accessible quantities that characterise the anharmonic elasticity and does not use details about the microscopic interactions. In particular, we express the TS characteristic exponent [Formula: see text] in terms of the lattice Grüneisen parameter [Formula: see text] and the isochoric anharmonicity [Formula: see text]. An analytic expression of the TS master curve of [Formula: see text] with [Formula: see text] as the key adjustable parameter is found. The comparison with the experimental TS master curves and the isochoric fragilities of 34 glassformers is satisfying. In a few cases, where thermodynamic data are available, we test (i) the predicted characteristic exponent [Formula: see text] and (ii) the isochoric anharmonicity [Formula: see text], as drawn by the best fit of the TS of the structural relaxation, against the available thermodynamic data. A linear relation between the isochoric fragility and the isochoric anharmonicity [Formula: see text] is found and compared favourably with the results of experiments with no adjustable parameters. A relation between the increase of the isochoric vibrational heat capacity due to anharmonicity and the isochoric fragility is derived.
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Affiliation(s)
- S Bernini
- Dipartimento di Fisica 'Enrico Fermi', Università di Pisa, Largo B Pontecorvo 3, I-56127 Pisa, Italy. Present address: Jawaharlal Nehru Center for Advanced Scientific Research, Theoretical Sciences Unit, Jakkur Campus, Bengaluru 560064, India
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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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Haghighi M, Tahir MN, Tremel W, Butt HJ, Steffen W. Translational and rotational diffusion of gold nanorods near a wall. J Chem Phys 2013; 139:064710. [DOI: 10.1063/1.4817405] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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Petzold N, Schmidtke B, Kahlau R, Bock D, Meier R, Micko B, Kruk D, Rössler EA. Evolution of the dynamic susceptibility in molecular glass formers: Results from light scattering, dielectric spectroscopy, and NMR. J Chem Phys 2013; 138:12A510. [DOI: 10.1063/1.4770055] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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11
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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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12
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13
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Maczka M, Hanuza J, Baran J, Hushur A, Kojima S. Heat capacity, Raman, and Brillouin scattering studies of M2O–MgO–WO3–P2O5 glasses (M=K,Rb). J Chem Phys 2006; 125:244503. [PMID: 17199351 DOI: 10.1063/1.2403127] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors report the results of temperature-dependent Brillouin scattering from both transverse and longitudinal acoustic waves, heat capacity studies as well as room temperature Raman scattering studies on M2O-MgO-WO3-P2O5 glasses (M=K,Rb). These results were used to obtain information about structure and various properties of the studied glasses such as fragility, elastic moduli, ratio of photoelastic constants, and elastic anharmonicity. They have found that both glasses have similar properties but replacement of K+ ions by Rb+ ions in the glass network leads to decrease of elastic parameters and P44 photoelastic constant due to increase of fragility. Based on Brillouin spectroscopy they show that a linear correlation between longitudinal and shear elastic moduli holds over a large temperature range. This result supports the literature data that the Cauchy-type relation represents a general rule for amorphous solids. An analysis of the Boson peak revealed that the form of the frequency distribution of the excess density of states is in agreement with the Euclidean random matrix theory. The reason of the observed shift of the maximum frequency of the Boson peak when K+ ions are substituted for Rb+ ions is also briefly discussed.
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Affiliation(s)
- M Maczka
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2, Poland
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14
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Roland CM, Capaccioli S, Lucchesi M, Casalini R. Adam–Gibbs model for the supercooled dynamics in the ortho-terphenyl ortho-phenylphenol mixture. J Chem Phys 2004; 120:10640-6. [PMID: 15268090 DOI: 10.1063/1.1739394] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Dielectric measurements of the alpha-relaxation time were carried out on a mixture of ortho-terphenyl (OTP) with ortho-phenylphenol, over a range of temperatures at two pressures, 0.1 and 28.8 MPa. These are the same conditions for which heat capacity, thermal expansivity, and compressibility measurements were reported by Takahara et al. [S. Takahara, M. Ishikawa, O. Yamamuro, and T. Matsuo, J. Phys. Chem. B 103, 3288 (1999)] for the same mixture. From the combined dynamic and thermodynamic data, we determine that density and temperature govern to an equivalent degree the variation of the relaxation times with temperature. Over the measured range, the dependence of the relaxation times on configurational entropy is in accord with the Adam-Gibbs model, and this dependence is invariant to pressure. Consistent with the implied connection between relaxation and thermodynamic properties, the kinetic and thermodynamic fragilities are found to have the same pressure independence. In comparing the relaxation properties of the mixture to those of neat OTP, density effects are stronger in the former, perhaps suggestive of less efficient packing.
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Affiliation(s)
- C M Roland
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington, DC 20375-5342, USA.
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Patkowski A, Matos Lopes M, Fischer EW. Pressure dependence of the high-frequency light scattering susceptibility of ortho-terphenyl: A mode coupling analysis. J Chem Phys 2003. [DOI: 10.1063/1.1581847] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Scodinu A, Fourkas JT. Intermolecular Dynamics and Structure of Carbon Disulfide in Isoviscous Alkane Solutions: An Optical Kerr Effect Study. J Phys Chem B 2002. [DOI: 10.1021/jp026359m] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alessandra Scodinu
- Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467
| | - John T. Fourkas
- Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467
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Mossa S, Ruocco G, Sampoli M. Orientational and induced contributions to the depolarized Rayleigh spectra of liquid and supercooled ortho-terphenyl. J Chem Phys 2002. [DOI: 10.1063/1.1493774] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Patkowski A, Fischer EW, Steffen W, Gläser H, Baumann M, Ruths T, Meier G. Unusual features of long-range density fluctuations in glass-forming organic liquids: a Rayleigh and Rayleigh-Brillouin light scattering study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:061503. [PMID: 11415106 DOI: 10.1103/physreve.63.061503] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2001] [Indexed: 05/23/2023]
Abstract
A new feature of glass-forming liquids, i.e., long-range density fluctuations of the order of 100 nm, has been extensively characterized by means of static light scattering, photon correlation spectroscopy and Rayleigh-Brillouin spectroscopy in orthoterphenyl (OTP) and 1,1-di(4(')-methoxy-5(')methyl-phenyl)-cyclohexane (BMMPC). These long-range density fluctuations result in the following unusual features observed in a light scattering experiment, which are not described by the existing theories: (i) strong q-dependent isotropic excess Rayleigh intensity, (ii) additional slow component in the polarized photon correlation function, and (iii) high Landau-Placzek ratio. These unusual features are equilibrium properties of the glass-forming liquids and depend only on temperature, provided that the sample has been equilibrated long enough. The temperature-dependent equilibration times were measured for BMMPC and are about 11 orders of magnitude longer than the alpha process. It was found that the glass-forming liquid OTP may occur in two states: with and without long-range density fluctuations ("clusters"). We have characterized the two states by static and dynamic light scattering in the temperature range from T(g) to T(g)+200 K. The relaxation times of the alpha process as well as the parameters of the Brillouin line are identical in both OTP with and without clusters. The alpha process (density fluctuations) in OTP was characterized by measuring either the polarized (VV) or depolarized (VH) correlation function, which are practically identical and q-independent. This feature, which is commonly observed in glass-forming liquids, is not fully explained by the existing theories.
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Affiliation(s)
- A Patkowski
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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Monaco G, Fioretto D, Comez L, Ruocco G. Glass transition and density fluctuations in the fragile glass former orthoterphenyl. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:061502. [PMID: 11415105 DOI: 10.1103/physreve.63.061502] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2000] [Revised: 02/12/2001] [Indexed: 05/23/2023]
Abstract
High-resolution Brillouin light scattering is used to measure the dynamic structure factor of the fragile glass former orthoterphenyl (OTP) in a wide temperature range around the glass transition region and up to the boiling point. The whole set of spectra is described in terms of a phenomenological generalized hydrodynamic model. In the supercooled phase, we show the contemporary existence of the structural process, whose main features come out to be consistent with the results obtained with other spectroscopies, and of a secondary, activated process, which occurs on the 10(-11) s time scale and has a low activation energy (E(f)(a)=0.28 kcal/mol). This latter process, which is also present in the glassy phase and seems to be insensitive to the glass transition, is attributed to the coupling between the density modes and intramolecular degrees of freedom. In the normal liquid phase, the two processes merge together, and the resulting characteristic time is no longer consistent with those derived with other spectroscopies. The analysis points to the conclusion that, for what concerns the long-wavelength density fluctuations in fragile glass formers such as OTP, the universal dynamical features related to the glass transition come out clearly only in the supercooled phase and at frequencies lower than approximately 10(6) Hz.
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Affiliation(s)
- G Monaco
- European Synchrotron Radiation Facility, Boîte Postale 220, F-38042 Grenoble Cedex 9, France
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20
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Blochowicz T, Kudlik A, Benkhof S, Senker J, Rössler E, Hinze G. The spectral density in simple organic glass formers: Comparison of dielectric and spin-lattice relaxation. J Chem Phys 1999. [DOI: 10.1063/1.479178] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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21
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Chirico G, Gardella M. Photon cross-correlation spectroscopy to 10-ns resolution. APPLIED OPTICS 1999; 38:2059-2067. [PMID: 18319764 DOI: 10.1364/ao.38.002059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe a low-cost modification based on the research of Arecchi et al. [Opt. Commun. 3, 284-288 (1971)] on a standard photon correlation spectroscopy setup for measuring small (approximately equal 1%) and fast (resolution, approximately equal 10 ns) light fluctuations. Details of the electronics and optics permit the apparatus to be easily reproduced. Careful tests show that spurious correlations of <or=1% can be achieved with standard detectors only when taking precautions with the electronics. Moreover, measurements on latex spheres, ellipsoids, and protein solutions show that fast and very small light fluctuations ( approximately equal 1-5%) can be studied versus scattering vector and light polarization.
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Affiliation(s)
- G Chirico
- Dipartimento di Fisica, Istituto Nazionale di Fisica per la Materia, Via Celoria 16, I-20131 Milano, Italy
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22
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Murry RL, Fourkas JT, Keyes T. Nonresonant intermolecular spectroscopy beyond the Placzek approximation. II. Fifth-order spectroscopy. J Chem Phys 1998. [DOI: 10.1063/1.477439] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Murry RL, Fourkas JT, Keyes T. Nonresonant intermolecular spectroscopy beyond the Placzek approximation. I. Third-order spectroscopy. J Chem Phys 1998. [DOI: 10.1063/1.476850] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Murry RL, Fourkas JT. Polarization selectivity of nonresonant spectroscopies in isotropic media. J Chem Phys 1997. [DOI: 10.1063/1.475269] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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