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Shklyaev OE, Cole MW, Crespi VH. Adsorption-induced shape transitions in bistable nanopores with atomically thin walls. Phys Rev E 2017; 95:012804. [PMID: 28208324 DOI: 10.1103/physreve.95.012804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Indexed: 11/07/2022]
Abstract
Atomically thin cylindrical nanopores can change shape in response to physically adsorbed gas inside. Coupled to a gas reservoir, an initially collapsed pore can expand to allow the adsorbed gas to form concentric shells on the inner part of the pore, driven by adsorption energetics, not gas pressure. A lattice gas model describes the evolution of the nanotube pore shape and absorbed gas as a function of gas chemical potential at zero temperature. We found that narrow-enough tubes are always expanded and gas inside adsorbs in sequences of concentric shells as the gas chemical potential increases. Wider tubes, which are collapsed without gas, can expand with one or more concentric shells adsorbed on the inner surface of the expanded region.
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Affiliation(s)
- Oleg E Shklyaev
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802-6300, USA
| | - Milton W Cole
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802-6300, USA
| | - Vincent H Crespi
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802-6300, USA
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Pinto OA, Pasinetti PM, Ramirez-Pastor AJ, Nieto FD. The adsorption of a mixture of particles with non-additive interactions: a Monte Carlo study. Phys Chem Chem Phys 2015; 17:3050-8. [PMID: 25512955 DOI: 10.1039/c4cp04428b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The adsorption of binary mixtures with non-additive lateral interactions has been studied through grand canonical Monte Carlo simulations in the framework of the lattice-gas model. The traditional assumption of additive lateral interactions is replaced with a more general one including non-pairwise interactions. It is assumed that the energy linking a certain atom with any of its nearest neighbors strongly depends on the state of occupancy in the first coordination sphere of such an adatom. The process has been monitored through the adsorption isotherms and the differential heats of adsorption. Different combinations of both inter- and intra-species interactions have been considered in the analysis. Interesting behaviors were observed and discussed in terms of the low temperature phases formed in the system.
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Affiliation(s)
- O A Pinto
- Centro de Investigaciones y Transferencia de Santiago del Estero, (CITSE-CONICET) Universidad de Santiago de Estero, RN 9 Km 1125 Villa el Zanjón, Santiago del Estero, CP 4206 Argentina.
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Vann JM, Molnar SL, Mercedes Calbi M. Equilibration processes during gas uptake inside narrow pores. Phys Chem Chem Phys 2015; 17:13021-7. [DOI: 10.1039/c5cp00502g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We analyze the adsorption kinetics of a gas in contact with the open ends of a narrow longitudinal pore, where gas transport along its interior occursviasingle-file diffusion mechanisms.
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Affiliation(s)
- Joshua M. Vann
- Department of Physics and Astronomy
- University of Denver
- Denver
- USA
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4
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Pinto OA, Pasinetti PM, Nieto F, Ramirez-Pastor AJ. Lattice-gas model of nonadditive interacting particles on nanotube bundles. J Chem Phys 2011; 134:064702. [PMID: 21322716 DOI: 10.1063/1.3530788] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In the present paper, the adsorption thermodynamics of a lattice-gas model which mimics a nanoporous environment is studied by considering nonadditive interactions between the adsorbed particles. It is assumed that the energy linking a certain atom with any of its nearest neighbors strongly depends on the state of occupancy in the first coordination sphere of such an adatom. By means of Monte Carlo (MC) simulations in the grand canonical ensemble, adsorption isotherms and differential heats of adsorption were calculated. Their striking behaviors were analyzed and discussed in terms of the low temperature phases formed in the system. Finally, the results obtained from MC simulations were compared with the corresponding ones from Bragg-Williams approximation.
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Affiliation(s)
- O A Pinto
- Departamento de Física, Instituto de Física Aplicada (INFAP), Universidad Nacional de San Luis, CONICET, Chacabuco 917, D5700BWS, San Luis, Argentina
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Pasinetti PM, Romá F, Riccardo JL, Ramirez-Pastor AJ. Critical behavior of interacting monomers adsorbed on one-dimensional channels arranged in a triangular cross-sectional structure: mixed interactions along and across the channels. J Chem Phys 2010; 132:054111. [PMID: 20136309 DOI: 10.1063/1.3292680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Monte Carlo simulations and finite-size scaling analysis have been carried out to study the critical behavior in a submonolayer lattice-gas which mimics a nanoporous environment. In this model, the adsorbent is modeled as one-dimensional channels of equivalent adsorption sites arranged in a triangular cross-sectional structure. Two kinds of lateral interaction energies have been considered: (1) w(L) interaction energy between nearest-neighbor particles adsorbed along a single channel and (2) w(T) interaction energy between particles adsorbed across nearest-neighbor channels. We focus on the case of repulsive transverse (w(T)>0) and attractive longitudinal (w(L)<0) lateral interactions, where a rich variety of structural orderings are observed in the adlayer depending on the value of the parameters k(B)T/w(T) (being k(B) the Boltzmann constant) and w(L)/w(T). The results reveal the existence of a first-order phase transition in the adlayer between a low-temperature "condensed" phase and a high-temperature "disordered" phase.
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Affiliation(s)
- P M Pasinetti
- Departamento de Física, Instituto de Física Aplicada, Universidad Nacional de San Luis, CONICET, Chacabuco 917, 5700 San Luis, Argentina.
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Albesa AG, Fertitta EA, Vicente JL. Comparative study of methane adsorption on single-walled carbon nanotubes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:786-795. [PMID: 19899786 DOI: 10.1021/la902192a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present the combined results of ab initio and molecular mechanical calculations, computer simulations, and adsorption isotherms investigations of CH(4) adsorbed on HiPco single-walled carbon nanotubes. Isotherms and adsorption energies obtained in our model and simulations are in good agreement with ours and others experimental results. The theoretical analysis conducted for various homogeneous bundles of close-ended and open-ended tubes confirm not only the adsorption in at least two different stages but also the role played by each of the different adsorption sites on the nanotube bundles. The study of different site and nanotube sizes allows us to establish the presence of open tubes in the as-produced HiPco bundles, without regarding the role that adsorption in large interstitial channels may play. Our results also show that predicted scenarios, for the mechanism and the preferential adsorption sites depend on the size of the nanotubes and those of the bundles.
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Affiliation(s)
- Alberto G Albesa
- Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas, Departamento de Quimica, Facultad de Ciencias Exactas, UNLP, CC 16, Suc. 4 (1900) La Plata, Argentina
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7
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Statistical mechanical lattice models of endohedral and exohedral xenon adsorption in carbon nanotubes and comparison with Monte-Carlo simulations. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.11.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
We suggest that bubbles are the bistable hydrophobic gates responsible for the on-off transitions of single channel currents. In this view, many types of channels gate by the same physical mechanism-dewetting by capillary evaporation-but different types of channels use different sensors to modulate hydrophobic properties of the channel wall and thereby trigger and control bubbles and gating. Spontaneous emptying of channels has been seen in many simulations. Because of the physics involved, such phase transitions are inherently sensitive, unstable threshold phenomena that are difficult to simulate reproducibly and thus convincingly. We present a thermodynamic analysis of a bubble gate using morphometric density functional theory of classical (not quantum) mechanics. Thermodynamic analysis of phase transitions is generally more reproducible and less sensitive to details than simulations. Anesthetic actions of inert gases-and their interactions with hydrostatic pressure (e.g., nitrogen narcosis)-can be easily understood by actions on bubbles. A general theory of gas anesthesia may involve bubbles in channels. Only experiments can show whether, or when, or which channels actually use bubbles as hydrophobic gates: direct observation of bubbles in channels is needed. Existing experiments show thin gas layers on hydrophobic surfaces in water and suggest that bubbles nearly exist in bulk water.
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Pasinetti PM, Romá F, Riccardo JL, Ramirez-Pastor AJ. Surface phase transitions in one-dimensional channels arranged in a triangular cross-sectional structure: theory and Monte Carlo simulations. J Chem Phys 2006; 125:214705. [PMID: 17166038 DOI: 10.1063/1.2397682] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Monte Carlo simulations and finite-size scaling analysis have been carried out to study the critical behavior in a submonolayer lattice-gas of interacting monomers adsorbed on one-dimensional channels arranged in a triangular cross-sectional structure. Two kinds of lateral interaction energies have been considered: (1) w(L), interaction energy between nearest-neighbor particles adsorbed along a single channel and (2) w(T), interaction energy between particles adsorbed across nearest-neighbor channels. We focus on the case of repulsive transverse interactions (w(T)>0), where a rich variety of structural orderings are observed in the adlayer, depending on the value of the parameters k(B)Tw(T) (being k(B) the Boltzmann constant) and w(L)w(T). For w(L)w(T)=0, successive planes are uncorrelated, the system is equivalent to the triangular lattice, and the well-known ([square root] 3 x [square root] 3) [([square root] 3 x ([square root] 3)(*)] ordered phase is found at low temperatures and a coverage, theta, of 13. In the more general case (w(L)/w(T) not equal 0), a competition between interactions along a single channel and a transverse coupling between sites in neighboring channels leads to a three-dimensional adsorbed layer. Consequently, the ([square root] 3 x ([square root] 3) and (([square root] 3 x ([square root] 3)(*) structures "propagate" along the channels and new ordered phases appear in the adlayer. Each ordered phase is separated from the disordered state by a continuous order-disorder phase transition occurring at a critical temperature, T(c), which presents an interesting dependence with w(L)/w(T). The Monte Carlo technique was combined with the recently reported free energy minimization criterion approach (FEMCA) [F. Roma et al., Phys. Rev. B 68, 205407 (2003)] to predict the critical temperatures of the order-disorder transformation. The excellent qualitative agreement between simulated data and FEMCA results allows us to interpret the physical meaning of the mechanisms underlying the observed transitions.
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Affiliation(s)
- P M Pasinetti
- Departamento de Física, Universidad Nacional de San Luis, CONICET, Chacabuco 917, 5700 San Luis, Argentina
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Jakubek ZJ, Simard B. Endohedral condensation and higher exohedral coverage of Kr on open single-walled carbon nanotubes at 77 K. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:10730-4. [PMID: 16262344 DOI: 10.1021/la050510c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
An isotherm quasi-discontinuity, or a near-vertical step, at 177 microTorr indicative of Kr condensation inside open single-walled carbon nanotubes (SWNT) has been observed at 77 K. The isotherm shows double adsorption-branch structure attributed to the existence of two endohedral phases of confined Kr. Three well-pronounced steps corresponding to the formation of various exohedral phases are present in the high-density (low-pressure) branch. The desorption branch exhibits three rounded steps assigned to higher order exohedral coverage.
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Affiliation(s)
- Zygmunt J Jakubek
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa.
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Pasinetti PM, Riccardo JL, Ramirez-Pastor AJ. Configurational entropy of interacting particles adsorbed on one-dimensional channels arranged in a triangular structure. J Chem Phys 2005; 122:154708. [PMID: 15945657 DOI: 10.1063/1.1884106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The configurational entropy of interacting particles adsorbed on one-dimensional channels arranged in a triangular cross-sectional structure is studied by combining Monte Carlo simulation and thermodynamic integration method. Three different energies have been considered in the adsorption process: (1) epsilono, constant interaction energy between a monomer and an adsorption site; (2) wL, interaction energy between nearest-neighbor particles adsorbed along a single channel, and (3) wT, interaction energy between particles adsorbed across nearest-neighbor channels. Special attention is devoted to the case of repulsive transversal interactions (wT>0), for which a rich variety of ordered phases are observed in the adlayer, depending on the value of the parameters kBT/wT (being kB the Boltzmann constant) and wL/wT. The influence of each ordered structure on the configurational entropy of the adlayer has been analyzed and discussed in the context of the lattice-gas model.
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Affiliation(s)
- P M Pasinetti
- Departamento de Física, Universidad Nacional de San Luis, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Chacabuco 917, 5700 San Luis, Argentina
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Trasca RA, Calbi MM, Cole MW, Riccardo JL. Lattice-gas Monte Carlo study of adsorption in pores. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:011605. [PMID: 14995631 DOI: 10.1103/physreve.69.011605] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Indexed: 05/24/2023]
Abstract
A lattice-gas model of adsorption inside cylindrical pores is evaluated with Monte Carlo simulations. The model incorporates two kinds of sites: (a line of) "axial" sites and surrounding "cylindrical shell" sites, in the ratio 1:7. The adsorption isotherms are calculated in either the grand canonical or canonical ensembles. At low temperature, there occur quasitransitions that would be genuine thermodynamic transitions in mean-field theory. Comparisons between the Monte Carlo and mean-field theory results for the heat capacity and adsorption isotherms are provided.
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Affiliation(s)
- Raluca A Trasca
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Maibaum L, Chandler D. A Coarse-Grained Model of Water Confined in a Hydrophobic Tube. J Phys Chem B 2003. [DOI: 10.1021/jp0267196] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lutz Maibaum
- Department of Chemistry, University of California, Berkeley, California 94720
| | - David Chandler
- Department of Chemistry, University of California, Berkeley, California 94720
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