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Ranieri U, Formisano F, Gorelli FA, Santoro M, Koza MM, De Francesco A, Bove LE. Crossover from gas-like to liquid-like molecular diffusion in a simple supercritical fluid. Nat Commun 2024; 15:4142. [PMID: 38755136 PMCID: PMC11099187 DOI: 10.1038/s41467-024-47961-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/15/2024] [Indexed: 05/18/2024] Open
Abstract
According to textbooks, no physical observable can be discerned allowing to distinguish a liquid from a gas beyond the critical point. Yet, several proposals have been put forward challenging this view and various transition boundaries between a gas-like and a liquid-like behaviour, including the so-called Widom and Frenkel lines, and percolation line, have been suggested to delineate the supercritical state space. Here we report observation of a crossover from gas-like (Gaussian) to liquid-like (Lorentzian) self-dynamic structure factor by incoherent quasi-elastic neutron scattering measurements on supercritical fluid methane as a function of pressure, along the 200 K isotherm. The molecular self-diffusion coefficient was derived from the best Gaussian (at low pressures) or Lorentzian (at high pressures) fits to the neutron spectra. The Gaussian-to-Lorentzian crossover is progressive and takes place at about the Widom line intercept (59 bar). At considerably higher pressures, a liquid-like jump diffusion mechanism properly describes the supercritical fluid on both sides of the Frenkel line. The present observation of a gas-like to liquid-like crossover in the self dynamics of a simple supercritical fluid confirms emerging views on the unexpectedly complex physics of the supercritical state, and could have planet-wide implications and possible industrial applications in green chemistry.
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Affiliation(s)
- Umbertoluca Ranieri
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, Roma, 00187, Italy
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Ferdinando Formisano
- CNR - Istituto Officina dei Materiali (IOM), Grenoble, INSIDE@ILL, 71 Avenue des Martyrs, Grenoble, Cedex 9, France.
- Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble, Cedex 9, France.
| | - Federico A Gorelli
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai, 201203, China.
- Shanghai Advanced Research in Physical Sciences (SHARPS), Pudong, Shanghai, 201203, China.
- Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, CNR-INO, Via Nello Carrara 1, Sesto Fiorentino (FI), 50019, Italy.
| | - Mario Santoro
- Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, CNR-INO, Via Nello Carrara 1, Sesto Fiorentino (FI), 50019, Italy
- European Laboratory for Nonlinear Spectroscopy, LENS, Via Nello Carrara 1, Sesto Fiorentino (FI), 50019, Italy
| | - Michael Marek Koza
- Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble, Cedex 9, France
| | - Alessio De Francesco
- CNR - Istituto Officina dei Materiali (IOM), Grenoble, INSIDE@ILL, 71 Avenue des Martyrs, Grenoble, Cedex 9, France
- Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble, Cedex 9, France
| | - Livia E Bove
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, Roma, 00187, Italy
- Laboratory of Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, 5 Place Jussieu, Paris, 75005, France
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Simeski F, Ihme M. Supercritical fluids behave as complex networks. Nat Commun 2023; 14:1996. [PMID: 37032390 PMCID: PMC10083177 DOI: 10.1038/s41467-023-37645-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 03/22/2023] [Indexed: 04/11/2023] Open
Abstract
Supercritical fluids play a key role in environmental, geological, and celestial processes, and are of great importance to many scientific and engineering applications. They exhibit strong variations in thermodynamic response functions, which has been hypothesized to stem from the microstructural behavior. However, a direct connection between thermodynamic conditions and the microstructural behavior, as described by molecular clusters, remains an outstanding issue. By utilizing a first-principles-based criterion and self-similarity analysis, we identify energetically localized molecular clusters whose size distribution and connectivity exhibit self-similarity in the extended supercritical phase space. We show that the structural response of these clusters follows a complex network behavior whose dynamics arises from the energetics of isotropic molecular interactions. Furthermore, we demonstrate that a hidden variable network model can accurately describe the structural and dynamical response of supercritical fluids. These results highlight the need for constitutive models and provide a basis to relate the fluid microstructure to thermodynamic response functions.
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Affiliation(s)
- Filip Simeski
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Matthias Ihme
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA.
- Department of Photon Science, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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Abstract
It is demonstrated that the crossover between gas- and liquid-like regions on the phase diagram of the Lennard-Jones system occurs at a fixed value of the density divided by its value at the freezing point, ρ/ ρfr ≃ 0.35. This definition is consistent with other definitions proposed recently. As a result, a very simple practical expression for the gas-to-liquid crossover line emerges.
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Affiliation(s)
- S. A. Khrapak
- Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow, Russia
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Zanetti-Polzi L, Daidone I, Amadei A. A general statistical mechanical model for fluid system thermodynamics: Application to sub- and super-critical water. J Chem Phys 2022; 156:044506. [DOI: 10.1063/5.0079206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Laura Zanetti-Polzi
- Center S3, CNR-Institute of Nanoscience, Via Campi 213/A, 41125 Modena, Italy
| | - Isabella Daidone
- Department of Physical and Chemical Sciences, University of L’Aquila, via Vetoio (Coppito 1), 67010 L’Aquila, Italy
| | - Andrea Amadei
- Department of Chemical and Technological Sciences, University of Rome “Tor Vergata”, Via della Ricerca Scientifica, I-00185 Rome, Italy
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Sun P, Hastings JB, Ishikawa D, Baron AQR, Monaco G. Universal Two-Component Dynamics in Supercritical Fluids. J Phys Chem B 2021; 125:13494-13501. [PMID: 34855409 PMCID: PMC8686117 DOI: 10.1021/acs.jpcb.1c07900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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Despite the technological importance of supercritical fluids, controversy remains
about the details of their microscopic dynamics. In this work, we
study four supercritical fluid systems—water, Si, Te, and Lennard-Jones
fluid—via classical molecular dynamics simulations. A universal
two-component behavior is observed in the intermolecular dynamics
of these systems, and the changing ratio between the two components
leads to a crossover from liquidlike to gaslike dynamics, most rapidly
around the Widom line. We find evidence to connect the liquidlike
component dominating at lower temperatures with intermolecular bonding
and the component prominent at higher temperatures with free-particle,
gaslike dynamics. The ratio between the components can be used to
describe important properties of the fluid, such as its self-diffusion
coefficient, in the transition region. Our results provide an insight
into the fundamental mechanism controlling the dynamics of supercritical
fluids and highlight the role of spatiotemporally inhomogeneous dynamics
even in thermodynamic states where no large-scale fluctuations exist
in the fluid.
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Affiliation(s)
- Peihao Sun
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States.,Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, United States
| | - J B Hastings
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Daisuke Ishikawa
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Alfred Q R Baron
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Giulio Monaco
- Dipartimento di Fisica e Astronomia, Università di Padova, 35131 Padova, Italy
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