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Gandolfi M, Liu L, Zhang P, Kouyaté M, Salenbien R, Banfi F, Glorieux C. Revisiting impulsive stimulated thermal scattering in supercooled liquids: Relaxation of specific heat and thermal expansion. J Chem Phys 2021; 155:164501. [PMID: 34717363 DOI: 10.1063/5.0063805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Impulsive stimulated thermal scattering (ISTS) allows one to access the structural relaxation dynamics in supercooled molecular liquids on a time scale ranging from nanoseconds to milliseconds. Till now, a heuristic semi-empirical model has been commonly adopted to account for the ISTS signals. This model implicitly assumes that the relaxation of specific heat, C, and thermal expansion coefficient, γ, occur on the same time scale and accounts for them via a single stretched exponential. This work proposes two models that assume disentangled relaxations, respectively, based on the Debye and Havriliak-Negami assumptions for the relaxation spectrum and explicitly accounting for the relaxation of C and γ separately in the ISTS response. A theoretical analysis was conducted to test and compare the disentangled relaxation models against the stretched exponential. The former models were applied to rationalize the experimental ISTS signals acquired on supercooled glycerol. This allows us to simultaneously retrieve the frequency-dependent specific heat and thermal expansion up to the sub-100 MHz frequency range and further to compare the fragility and time scale probed by thermal, mechanical, and dielectric susceptibilities.
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Affiliation(s)
- Marco Gandolfi
- CNR-INO (National Institute of Optics), Via Branze 45, 25123 Brescia, Italy
| | - Liwang Liu
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | - Pengfei Zhang
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | - Mansour Kouyaté
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | | | - Francesco Banfi
- FemtoNanoOptics Group, Université de Lyon, CNRS, Université Claude Bernard Lyon 1, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Christ Glorieux
- Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
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Robbins AB, Drakopoulos SX, Martin-Fabiani I, Ronca S, Minnich AJ. Ballistic thermal phonons traversing nanocrystalline domains in oriented polyethylene. Proc Natl Acad Sci U S A 2019; 116:17163-17168. [PMID: 31405988 PMCID: PMC6717268 DOI: 10.1073/pnas.1905492116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Thermally conductive polymer crystals are of both fundamental and practical interest for their high thermal conductivity that exceeds that of many metals. In particular, polyethylene fibers and oriented films with uniaxial thermal conductivity exceeding 50 [Formula: see text] have been reported recently, stimulating interest into the underlying microscopic thermal transport processes. While ab initio calculations have provided insight into microscopic phonon properties for perfect crystals, such properties of actual samples have remained experimentally inaccessible. Here, we report the direct observation of thermal phonons with mean free paths up to 200 nm in semicrystalline polyethylene films using transient grating spectroscopy. Many of the mean free paths substantially exceed the crystalline domain sizes measured using small-angle X-ray scattering, indicating that thermal phonons propagate ballistically within and across the nanocrystalline domains; those transmitting across domain boundaries contribute nearly one-third of the thermal conductivity. Our work provides a direct determination of thermal phonon propagation lengths in molecular solids, yielding insights into the microscopic origins of their high thermal conductivity.
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Affiliation(s)
- Andrew B Robbins
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125
| | - Stavros X Drakopoulos
- Department of Materials, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | | | - Sara Ronca
- Department of Materials, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | - Austin J Minnich
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125;
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Sander M, Herzog M, Pudell JE, Bargheer M, Weinkauf N, Pedersen M, Newby G, Sellmann J, Schwarzkopf J, Besse V, Temnov VV, Gaal P. Spatiotemporal Coherent Control of Thermal Excitations in Solids. PHYSICAL REVIEW LETTERS 2017; 119:075901. [PMID: 28949697 DOI: 10.1103/physrevlett.119.075901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Indexed: 06/07/2023]
Abstract
X-ray reflectivity measurements of femtosecond laser-induced transient gratings (TG) are applied to demonstrate the spatiotemporal coherent control of thermally induced surface deformations on ultrafast time scales. Using grazing incidence x-ray diffraction we unambiguously measure the amplitude of transient surface deformations with sub-Å resolution. Understanding the dynamics of femtosecond TG excitations in terms of superposition of acoustic and thermal gratings makes it possible to develop new ways of coherent control in x-ray diffraction experiments. Being the dominant source of TG signal, the long-living thermal grating with spatial period Λ can be canceled by a second, time-delayed TG excitation shifted by Λ/2. The ultimate speed limits of such an ultrafast x-ray shutter are inferred from the detailed analysis of thermal and acoustic dynamics in TG experiments.
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Affiliation(s)
- M Sander
- Institute for Physics and Astronomy, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - M Herzog
- Institute for Physics and Astronomy, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - J E Pudell
- Institute for Physics and Astronomy, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - M Bargheer
- Institute for Physics and Astronomy, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
- Helmholtz-Zentrum Berlin for Materials and Energy GmbH, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin Germany
| | - N Weinkauf
- Institute for Solid State and Nanostructure Physics, Universität Hamburg, JungiusStraße 11, 20355 Hamburg, Germany
| | - M Pedersen
- European Synchrotron Radiation Facility ESRF, 71 Avenue des Martyrs 23800 Grenoble, France
| | - G Newby
- European Synchrotron Radiation Facility ESRF, 71 Avenue des Martyrs 23800 Grenoble, France
| | - J Sellmann
- Institute for Crystal Growth, Max-Born-Straße 2, 12489 Berlin, Germany
| | - J Schwarzkopf
- Institute for Crystal Growth, Max-Born-Straße 2, 12489 Berlin, Germany
| | - V Besse
- IMMM CNRS 6283, Université du Maine, 72085 Le Mans cedex, France
| | - V V Temnov
- IMMM CNRS 6283, Université du Maine, 72085 Le Mans cedex, France
- Groupe d'Etude de la Matière Condensée (GEMaC), Université de Versailles-Saint Quentin en Yvelines, CNRS UMR 8635, Université Paris-Sacley, 45 avenue des Etats-Unis, 78035 Versailles Cedex, France
| | - P Gaal
- Helmholtz-Zentrum Berlin for Materials and Energy GmbH, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin Germany
- Institute for Solid State and Nanostructure Physics, Universität Hamburg, JungiusStraße 11, 20355 Hamburg, Germany
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