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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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Khrapak SA, Khrapak AG. Freezing density scaling of transport coefficients in the Weeks-Chandler-Andersen fluid. J Chem Phys 2024; 160:134504. [PMID: 38557849 DOI: 10.1063/5.0199310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 03/13/2024] [Indexed: 04/04/2024] Open
Abstract
It is shown that the transport coefficients (self-diffusion, shear viscosity, and thermal conductivity) of the Weeks-Chandler-Andersen (WCA) fluid along isotherms exhibit a freezing density scaling (FDS). The functional form of this FDS is essentially the same or closely related to those in the Lennard-Jones fluid, hard-sphere fluid, and some liquefied noble gases. This proves that this FDS represents a quasi-universal corresponding state principle for simple classical fluids with steep interactions. Some related aspects, such as a Stokes-Einstein relation without a hydrodynamic diameter and gas-to-liquid dynamical crossover, are briefly discussed. Simple fitting formulas for the transport coefficients of the dense WCA fluid are suggested.
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Affiliation(s)
- S A Khrapak
- Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow, Russia
| | - A G Khrapak
- Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow, Russia
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Khrapak SA. System Size Dependence of the Diffusion Coefficients in MD Simulations: A Simple Correction Formula for Pure Dense Fluids. J Phys Chem B 2024; 128:287-290. [PMID: 38166419 DOI: 10.1021/acs.jpcb.3c07184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
A practical correction formula relating the self-diffusion coefficient of dense liquids from molecular dynamics (MD) simulations with periodic boundary conditions to the self-diffusion coefficient in the thermodynamic limit is discussed. This formula applies to pure dense fluids and has a very simple form D = D0(1 - γN-1/3), where D0 is the self-diffusion coefficient in the thermodynamic limit and N is the number of particles in the simulation. The numerical factor γ is dependent on the geometry of the simulation cell. Remarkably, γ ≃ 1.0 is the most popular cubic geometry. The success of this formula is supported by results from MD simulations, including very recent simulations with a "magic" simulation geometry.
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Affiliation(s)
- Sergey A Khrapak
- Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412, Russia
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Muhunthan P, Li H, Vignat G, Toro ER, Younes K, Sun Y, Sokaras D, Weiss T, Rajkovic I, Osaka T, Inoue I, Song S, Sato T, Zhu D, Fulton JL, Ihme M. A versatile pressure-cell design for studying ultrafast molecular-dynamics in supercritical fluids using coherent multi-pulse x-ray scattering. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:013901. [PMID: 38170817 PMCID: PMC10771079 DOI: 10.1063/5.0158497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 11/24/2023] [Indexed: 01/05/2024]
Abstract
Supercritical fluids (SCFs) can be found in a variety of environmental and industrial processes. They exhibit an anomalous thermodynamic behavior, which originates from their fluctuating heterogeneous micro-structure. Characterizing the dynamics of these fluids at high temperature and high pressure with nanometer spatial and picosecond temporal resolution has been very challenging. The advent of hard x-ray free electron lasers has enabled the development of novel multi-pulse ultrafast x-ray scattering techniques, such as x-ray photon correlation spectroscopy (XPCS) and x-ray pump x-ray probe (XPXP). These techniques offer new opportunities for resolving the ultrafast microscopic behavior in SCFs at unprecedented spatiotemporal resolution, unraveling the dynamics of their micro-structure. However, harnessing these capabilities requires a bespoke high-pressure and high-temperature sample system that is optimized to maximize signal intensity and address instrument-specific challenges, such as drift in beamline components, x-ray scattering background, and multi-x-ray-beam overlap. We present a pressure cell compatible with a wide range of SCFs with built-in optical access for XPCS and XPXP and discuss critical aspects of the pressure cell design, with a particular focus on the design optimization for XPCS.
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Affiliation(s)
- Priyanka Muhunthan
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Haoyuan Li
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Guillaume Vignat
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Edna R. Toro
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Khaled Younes
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Yanwen Sun
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | - Thomas Weiss
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Ivan Rajkovic
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Taito Osaka
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Ichiro Inoue
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Sanghoon Song
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Takahiro Sato
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Diling Zhu
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - John L. Fulton
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, USA
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Srinivasan H, Sharma VK, Sakai VG, Mukhopadhyay R, Mitra S. Noncanonical Relationship between Heterogeneity and the Stokes-Einstein Breakdown in Deep Eutectic Solvents. J Phys Chem Lett 2023; 14:9766-9773. [PMID: 37882461 DOI: 10.1021/acs.jpclett.3c02132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
The relationship between Stokes-Einstein breakdown (SEB) and dynamical heterogeneity (DH) is of paramount importance in the physical chemistry of complex fluids. In this work, we employ neutron scattering to probe the DH and SEB in a series of deep eutectic solvents (DESs) composed of acetamide and lithium salts. Quasielastic neutron scattering experiments reveal SEB in the jump diffusion of acetamide, represented by a fractional Stokes-Einstein relationship. Among these DESs, lithium perchlorate exhibits the most pronounced SEB while lithium bromide displays the weakest. Concurrently, elastic incoherent neutron scans identify that bromide DES is the most heterogeneous and perchlorate is the least. For the first time, our study unveils a counterintuitive incommensurate relationship between DH and SEB. Further, it reveals the intricate contrasting nature of the SEB-DH relationship when investigated in proximity to the glass-transition temperature and further away from it.
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Affiliation(s)
- H Srinivasan
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - V K Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - V García Sakai
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K
| | - R Mukhopadhyay
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - S Mitra
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
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Yasuda I, Kobayashi Y, Endo K, Hayakawa Y, Fujiwara K, Yajima K, Arai N, Yasuoka K. Combining Molecular Dynamics and Machine Learning to Analyze Shear Thinning for Alkane and Globular Lubricants in the Low Shear Regime. ACS APPLIED MATERIALS & INTERFACES 2023; 15:8567-8578. [PMID: 36715349 DOI: 10.1021/acsami.2c16366] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Lubricants with desirable frictional properties are important in achieving an energy-saving society. Lubricants at the interfaces of mechanical components are confined under high shear rates and pressures and behave quite differently from the bulk material. Computational approaches such as nonequilibrium molecular dynamics (NEMD) simulations have been performed to probe the molecular behavior of lubricants. However, the low-shear-velocity regions of the materials have rarely been simulated owing to the expensive calculations necessary to do so, and the molecular dynamics under shear velocities comparable with that in the experiments are not clearly understood. In this study, we performed NEMD simulations of extremely confined lubricants, i.e., two molecular layers for four types of lubricants confined in mica walls, under shear velocities from 0.001 to 1 m/s. While we confirmed shear thinning, the velocity profiles could not show the flow behavior when the shear velocity was much slower than thermal fluctuations. Therefore, we used an unsupervised machine learning approach to detect molecular movements that contribute to shear thinning. First, we extracted the simple features of molecular movements from large amounts of MD data, which were found to correlate with the effective viscosity. Subsequently, the extracted features were interpreted by examining the trajectories contributing to these features. The magnitude of diffusion corresponded to the viscosity, and the location of slips that varied depending on the spherical and chain lubricants was irrelevant. Finally, we attempted to apply a modified Stokes-Einstein relation at equilibrium to the nonequilibrium and confined systems. While systems with low shear rates obeyed the relation sufficiently, large deviations were observed under large shear rates.
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Affiliation(s)
- Ikki Yasuda
- Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa223-8522, Japan
| | - Yusei Kobayashi
- Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa223-8522, Japan
| | - Katsuhiro Endo
- Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa223-8522, Japan
| | - Yoshihiro Hayakawa
- Department of General Engineering, National Institute of Technology, Sendai College, Sendai, Miyagi989-3128, Japan
| | - Kazuhiko Fujiwara
- Department of General Engineering, National Institute of Technology, Sendai College, Sendai, Miyagi989-3128, Japan
| | - Kuniaki Yajima
- Department of General Engineering, National Institute of Technology, Sendai College, Sendai, Miyagi989-3128, Japan
| | - Noriyoshi Arai
- Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa223-8522, Japan
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa223-8522, Japan
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Qian F, Deng J, Dong Y, Xu C, Hu L, Fu G, Chang P, Xie Y, Sun J. Transfer-Free CVD Growth of High-Quality Wafer-Scale Graphene at 300 °C for Device Mass Fabrication. ACS APPLIED MATERIALS & INTERFACES 2022; 14:53174-53182. [PMID: 36383777 DOI: 10.1021/acsami.2c16505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Direct chemical vapor deposition of graphene on semiconductors and insulators provides high feasibility for integration of graphene devices and semiconductor electronics. However, the current methods typically rely on high temperatures (>1000 °C), which can damage the substrates. Here, a growth method for high-quality large-area graphene at 300 °C is introduced. A multizone furnace with gradient temperature control was designed according to a computational fluid dynamics model. The crucial roles of the chamber pressure in the film continuity and hydrogen composition in the graphene defect density at low temperature were revealed. As a result, a uniform graphene film with the Raman ratio ID/IG = 0.08 was obtained. Furthermore, a technique of laminating single-crystal Cu foil as a sacrificial layer on the substrate was proposed to realize transfer-free growth, and a wafer-scale graphene transistor array was demonstrated with good performance consistency, which paves the way for mass fabrication of graphene devices.
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Affiliation(s)
- Fengsong Qian
- Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing100124, China
| | - Jun Deng
- Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing100124, China
| | - Yibo Dong
- Institute of Photonic Chips, University of Shanghai for Science and Technology, Shanghai200093, China
| | - Chen Xu
- Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing100124, China
| | - Liangchen Hu
- Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing100124, China
| | - Guosheng Fu
- Fert Beijing Institute and School of Microelectronics, Beihang University, Beijing100191, China
| | - Pengying Chang
- Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing100124, China
| | - Yiyang Xie
- Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing100124, China
| | - Jie Sun
- National and Local United Engineering Laboratory of Flat Panel Display Technology, Fuzhou University, Fuzhou350100, China
- Mindu Innovation Laboratory, Fuzhou350100, China
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Khrapak SA, Khrapak A. Freezing density scaling of fluid transport properties: Application to liquified noble gases. J Chem Phys 2022; 157:014501. [DOI: 10.1063/5.0096947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A freezing density scaling of transport properties of the Lennard-Jones fluid is rationalized in terms of the Rosenfeld's excess entropy scaling and isomorph theory of Roskilde-simple systems. Then, it is demonstrated that the freezing density scaling operates reasonably well for viscosity and thermal conductivity coefficients of liquid argon, krypton, and xenon. Quasi-universality of the reduced transport coefficients at their minima and at freezing conditions is discussed. The magnitude of the thermal conductivity coefficient at the freezing point is shown to agree remarkably well with the prediction of the vibrational model of thermal transport in dense fluids.
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Affiliation(s)
- Sergey A. Khrapak
- Complex Plasma, FSBSI Joint Institute for High Temperatures of the Russian Academy of Sciences, Russia
| | - Alexey Khrapak
- Theoretical Department, Joint Institute for High Temperatures RAS, Russia
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10
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Gu Y, Liu B, Dai Q, Zhang Y, Zhou M, Feng Y, Hopke PK. Multiply improved positive matrix factorization for source apportionment of volatile organic compounds during the COVID-19 shutdown in Tianjin, China. ENVIRONMENT INTERNATIONAL 2022; 158:106979. [PMID: 34991244 DOI: 10.1016/j.envint.2021.106979] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/13/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Abstract
Ambient concentrations of volatile organic compounds (VOCs) vary with emission rates, meteorology, and chemistry. Conventional positive matrix factorization (PMF) loses information because of dilution variations and chemical losses. Multiply improved PMF incorporates the ventilation coefficient, and total solar radiation or oxidants to reduce the effects of dispersion and chemical loss. These methods were applied to hourly speciated VOC data from November 2019 to March 2020 including during the COVID-19 shutdown. Various comparisons were made to assess the influences of these fluctuation drivers by time of day. Dispersion normalized PMF (DN-PMF) reduced the dispersion variations. Dispersion-radiation normalized PMF (DRN-PMF) reduced the impact of chemical loss, especially at night, which was better than Dispersion-Ox normalized PMF (DON-PMF). The conditional bivariate probability function (CBPF) plots of DRN-PMF results were consist with actual source locations. The DN-PMF, DRN-PMF, and DON-PMF results were consistent between 10:00 and 15:00, suggesting dispersion was significantly more influential than photochemical reactions during these times. The DRN-PMF results indicated that the highest VOC contributors during the COVID-19 shutdown were liquefied petroleum gas (LPG) (28.8%), natural gas (25.2%), and pulverized coal boilers emissions (19.6%). Except for petrochemical-related enterprises and LPG, the contribution concentrations of all other sources decreased substantially during the COVID-19 shutdown, by 94.7%, 90.6%, and 86.8% for vehicle emissions, gasoline evaporation, and the mixed source of diesel evaporation and solvent use, respectively. Controlling the use of motor vehicles and related volatilization of diesel fuel and gasoline can be effective in controlling VOCs in the future.
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Affiliation(s)
- Yao Gu
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Baoshuang Liu
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China.
| | - Qili Dai
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Yufen Zhang
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Ming Zhou
- State Key Joint Laboratory of Environment Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Yinchang Feng
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Philip K Hopke
- Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA; Institute for a Sustainable Environment, Clarkson University, Potsdam, NY 13699, USA
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