Daniel Lozano-Martín, Rodrigo Susial, Pedro Hernández, Teresa E. Fernández-Vicente, M. Carmen Martín, José J. Segovia
This work presents phase envelope and speed of sound data for the (0.60 $CO_{2}$ + 0.40 $C_{3}H_{8}$) and (0.80 $CO_{2}$ + 0.20 $C_{3}H_{8}$) binary mixtures. Phase equilibria was measured using a cylindrical resonator working in the microwave band whereas an acoustic resonator was used for speed of sound measurements. The experimental results were compared with GERG-2008 equation of state, obtaining average absolute deviations by 0.24% in pressure for phase equilibria data and 0.025% for speed of sound data. Speed of sound values were used to derive perfect-gas heat capacities, acoustic virial coefficients, and second density virial coefficients. In addition, AGA8-DC92 equation of state performance was checked for the results derived from speeds of sound.
{"title":"Speed of sound and phase equilibria for ($CO_{2}$ + $C_{3}H_{8}$) mixtures","authors":"Daniel Lozano-Martín, Rodrigo Susial, Pedro Hernández, Teresa E. Fernández-Vicente, M. Carmen Martín, José J. Segovia","doi":"arxiv-2409.04083","DOIUrl":"https://doi.org/arxiv-2409.04083","url":null,"abstract":"This work presents phase envelope and speed of sound data for the (0.60\u0000$CO_{2}$ + 0.40 $C_{3}H_{8}$) and (0.80 $CO_{2}$ + 0.20 $C_{3}H_{8}$) binary\u0000mixtures. Phase equilibria was measured using a cylindrical resonator working\u0000in the microwave band whereas an acoustic resonator was used for speed of sound\u0000measurements. The experimental results were compared with GERG-2008 equation of\u0000state, obtaining average absolute deviations by 0.24% in pressure for phase\u0000equilibria data and 0.025% for speed of sound data. Speed of sound values were\u0000used to derive perfect-gas heat capacities, acoustic virial coefficients, and\u0000second density virial coefficients. In addition, AGA8-DC92 equation of state\u0000performance was checked for the results derived from speeds of sound.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yueqing Shi, Weike Quan, Liya Bi, Kangkai Liang, Hao Zhou, Zhiyuan Yin, Zihao Wang, Shaowei Li
Controlling the state of molecules on surfaces is crucial for the advancement of molecular electronics. While reversible control of bistable molecule switches has been demonstrated, achieving controllable multi-state switching at the molecular scale remains a formidable challenge. In this study, we introduce a simple and effective strategy for the on-demand control of a multi-level molecular switch by creating a molecular dimer. We explore the transition behavior of a pyrrolidine dimer system on the Cu(100) surface using low-temperature scanning tunneling microscopy. By fine-tuning the voltage and tip-molecule distance, we can selectively determine the dominant state of the dimer system. Both intermolecular and tip-molecule interactions play a role in modifying the transition pathways, enabling precise multi-state control.
{"title":"Operating a Multi-Level Molecular Dimer Switch through Precise Tip-Molecule Control","authors":"Yueqing Shi, Weike Quan, Liya Bi, Kangkai Liang, Hao Zhou, Zhiyuan Yin, Zihao Wang, Shaowei Li","doi":"arxiv-2409.04591","DOIUrl":"https://doi.org/arxiv-2409.04591","url":null,"abstract":"Controlling the state of molecules on surfaces is crucial for the advancement\u0000of molecular electronics. While reversible control of bistable molecule\u0000switches has been demonstrated, achieving controllable multi-state switching at\u0000the molecular scale remains a formidable challenge. In this study, we introduce\u0000a simple and effective strategy for the on-demand control of a multi-level\u0000molecular switch by creating a molecular dimer. We explore the transition\u0000behavior of a pyrrolidine dimer system on the Cu(100) surface using\u0000low-temperature scanning tunneling microscopy. By fine-tuning the voltage and\u0000tip-molecule distance, we can selectively determine the dominant state of the\u0000dimer system. Both intermolecular and tip-molecule interactions play a role in\u0000modifying the transition pathways, enabling precise multi-state control.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Francisco E. B. Bioucas, Carla S. G. P. Queirós, Daniel Lozano-Martín, M. S. Ferreira, Xavier Paredes, Ângela F. Santos, Fernando J. V. Santos, Manuel L. M. Lopes, Isabel M. S. Lampreia, Maria José V. Lourenço, Carlos A. Nieto de Castro, Klemens Massonne
Ionic liquids have proved to be excellent heat transfer fluids and alternatives to common HTFs used in industries for heat exchangers and other heat transfer equipment. However, its industrial utilization depends on the cost per kg of its production, to be competitive for industrial applications with biphenyl and diphenyl oxide, alkylated aromatics, and dimethyl polysiloxane oils, which degrade above 200 {deg}C and possess some environmental problems. The efficiency of a heat transfer fluid depends on the fundamental thermophysical properties influencing convective heat transfer (density, heat capacity, thermal conductivity, and viscosity), as these properties are necessary to calculate the heat transfer coefficients for different heat exchanger geometries. In Part 1, the thermophysical properties of pure 1-ethyl-3-methylimidazolium methanesulfonate $[C_{2}mim][CH_{3}SO_{3}]$ (CAS no. 145022-45-3), (ECOENG 110), produced by BASF, under the trade name of Basionics ST35, with an assay $geq$97% with $leq$0.5% water and $leq$2% chloride ($Cl^{-}$), were presented, for temperatures slightly below room temperature and up to 355 K. In this paper, we report the thermophysical properties of mixtures of [C2mim][CH3SO3] with water, in the whole concentration range, at $P$ = 0.1 MPa. The properties measured were density and speed of sound (293.15 < $T$/K < 343.15), viscosity, electrical and thermal conductivities, refractive index (293.15 < $T$/K < 353.15), and infinite dilution diffusion coefficient of the ionic liquid in water (298.15 K).
{"title":"$[C_{2}mim][CH_{3}SO_{3}]$ -- A Suitable New Heat Transfer Fluid? Part 2: Thermophysical Properties of Its Mixtures with Water","authors":"Francisco E. B. Bioucas, Carla S. G. P. Queirós, Daniel Lozano-Martín, M. S. Ferreira, Xavier Paredes, Ângela F. Santos, Fernando J. V. Santos, Manuel L. M. Lopes, Isabel M. S. Lampreia, Maria José V. Lourenço, Carlos A. Nieto de Castro, Klemens Massonne","doi":"arxiv-2409.04070","DOIUrl":"https://doi.org/arxiv-2409.04070","url":null,"abstract":"Ionic liquids have proved to be excellent heat transfer fluids and\u0000alternatives to common HTFs used in industries for heat exchangers and other\u0000heat transfer equipment. However, its industrial utilization depends on the\u0000cost per kg of its production, to be competitive for industrial applications\u0000with biphenyl and diphenyl oxide, alkylated aromatics, and dimethyl\u0000polysiloxane oils, which degrade above 200 {deg}C and possess some\u0000environmental problems. The efficiency of a heat transfer fluid depends on the\u0000fundamental thermophysical properties influencing convective heat transfer\u0000(density, heat capacity, thermal conductivity, and viscosity), as these\u0000properties are necessary to calculate the heat transfer coefficients for\u0000different heat exchanger geometries. In Part 1, the thermophysical properties\u0000of pure 1-ethyl-3-methylimidazolium methanesulfonate $[C_{2}mim][CH_{3}SO_{3}]$\u0000(CAS no. 145022-45-3), (ECOENG 110), produced by BASF, under the trade name of\u0000Basionics ST35, with an assay $geq$97% with $leq$0.5% water and $leq$2%\u0000chloride ($Cl^{-}$), were presented, for temperatures slightly below room\u0000temperature and up to 355 K. In this paper, we report the thermophysical\u0000properties of mixtures of [C2mim][CH3SO3] with water, in the whole\u0000concentration range, at $P$ = 0.1 MPa. The properties measured were density and\u0000speed of sound (293.15 < $T$/K < 343.15), viscosity, electrical and thermal\u0000conductivities, refractive index (293.15 < $T$/K < 353.15), and infinite\u0000dilution diffusion coefficient of the ionic liquid in water (298.15 K).","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lorenzo A. Mariano, Vu Ha Anh Nguyen, Valerio Briganti, Alessandro Lunghi
Magnetic anisotropy slows down magnetic relaxation and plays a prominent role in the design of permanent magnets. Coordination compounds of Co(II) in particular exhibit large magnetic anisotropy in the presence of low-coordination environments and have been used as single-molecule magnet prototypes. However, only a limited sampling of Cobalt's vast chemical space has been performed, potentially obscuring alternative chemical routes toward large magnetic anisotropy. Here we perform a computational high-throughput exploration of Co(II)'s chemical space in search of new single-molecule magnets. We automatically assemble a diverse set of about 15000 novel complexes of Co(II) and fully characterize them with multi-reference ab initio methods. More than 100 compounds exhibit magnetic anisotropy comparable to or larger than leading known compounds. The analysis of these results shows that compounds with record-breaking magnetic anisotropy can also be achieved with coordination four or higher, going beyond the established paradigm of two-coordinated linear complexes.
磁各向异性会减缓磁弛豫，在永磁体的设计中发挥着重要作用。特别是 Co（II）的配位化合物，在存在流配位环境时会表现出很大的磁各向异性，并已被用作单分子磁体原型。然而，人们只对钴的广阔化学空间进行了有限的取样，这可能掩盖了实现大磁各向异性的其他化学途径。在此，我们对钴（II）的化学空间进行了计算高通量探索，以寻找新的单分子磁体。我们自动组装了大约 15000 个新型 Co（II）配合物，并使用多参考ab initio 方法对它们进行了全面表征。对这些结果的分析表明，具有破纪录磁各向异性的化合物也可以通过四配位或更高配位实现，超越了双配位线性配合物的既定范例。
{"title":"Charting new regions of Cobalt's chemical space with maximally large magnetic anisotropy: A computational high-throughput study","authors":"Lorenzo A. Mariano, Vu Ha Anh Nguyen, Valerio Briganti, Alessandro Lunghi","doi":"arxiv-2409.04418","DOIUrl":"https://doi.org/arxiv-2409.04418","url":null,"abstract":"Magnetic anisotropy slows down magnetic relaxation and plays a prominent role\u0000in the design of permanent magnets. Coordination compounds of Co(II) in\u0000particular exhibit large magnetic anisotropy in the presence of\u0000low-coordination environments and have been used as single-molecule magnet\u0000prototypes. However, only a limited sampling of Cobalt's vast chemical space\u0000has been performed, potentially obscuring alternative chemical routes toward\u0000large magnetic anisotropy. Here we perform a computational high-throughput\u0000exploration of Co(II)'s chemical space in search of new single-molecule\u0000magnets. We automatically assemble a diverse set of about 15000 novel complexes\u0000of Co(II) and fully characterize them with multi-reference ab initio methods.\u0000More than 100 compounds exhibit magnetic anisotropy comparable to or larger\u0000than leading known compounds. The analysis of these results shows that\u0000compounds with record-breaking magnetic anisotropy can also be achieved with\u0000coordination four or higher, going beyond the established paradigm of\u0000two-coordinated linear complexes.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Samuel J. Pitman, Alicia K. Evans, Robbie T. Ireland, Felix Lempriere, Laura K. McKemmish
Basis sets are a crucial but often largely overlooked choice when setting up quantum chemistry calculations. The choice of basis set can be critical in determining the accuracy and calculation time of your quantum chemistry calculations. Clear recommendations based on thorough benchmarking are essential, but not readily available currently. This study investigates the relative quality of basis sets for general properties by benchmarking basis set performance for a diverse set of 136 reactions (from the diet-150-GMTKN55 dataset). In our analysis, we find the distributions of errors are often significantly non-Gaussian, meaning that the joint consideration of median errors, mean absolute errors and outlier statistics is helpful to provide a holistic understanding of basis set performance. Our direct comparison of performance between most modern basis sets provides quantitative evidence for basis set recommendations that broadly align with the established understanding of basis set experts and is evident in the design of modern basis sets. For example, while zeta is a good measure of quality, it is not the only determining factor for an accurate calculation with unpolarised double and triple-zeta basis sets (like 6-31G and 6-311G) having very poor performance. Appropriate use of polarisation functions (e.g. 6-31G*) is essential to obtain the accuracy offered by double or triple zeta basis sets. In our study, the best performance in our study for double and triple zeta basis set are 6-31++G** and pcseg-2 respectively. The polarised 6-311G basis set family has poor parameterisation which means its performance is more like a double-zeta than triple-zeta basis set. All versions of the 6-311G basis set family should be avoided entirely for valence chemistry calculations moving forward.
{"title":"Benchmarking Basis Sets for Density Functional Theory Thermochemistry Calculations: Why unpolarised basis sets and the polarised 6-311G family should be avoided","authors":"Samuel J. Pitman, Alicia K. Evans, Robbie T. Ireland, Felix Lempriere, Laura K. McKemmish","doi":"arxiv-2409.03964","DOIUrl":"https://doi.org/arxiv-2409.03964","url":null,"abstract":"Basis sets are a crucial but often largely overlooked choice when setting up\u0000quantum chemistry calculations. The choice of basis set can be critical in\u0000determining the accuracy and calculation time of your quantum chemistry\u0000calculations. Clear recommendations based on thorough benchmarking are\u0000essential, but not readily available currently. This study investigates the\u0000relative quality of basis sets for general properties by benchmarking basis set\u0000performance for a diverse set of 136 reactions (from the diet-150-GMTKN55\u0000dataset). In our analysis, we find the distributions of errors are often\u0000significantly non-Gaussian, meaning that the joint consideration of median\u0000errors, mean absolute errors and outlier statistics is helpful to provide a\u0000holistic understanding of basis set performance. Our direct comparison of\u0000performance between most modern basis sets provides quantitative evidence for\u0000basis set recommendations that broadly align with the established understanding\u0000of basis set experts and is evident in the design of modern basis sets. For\u0000example, while zeta is a good measure of quality, it is not the only\u0000determining factor for an accurate calculation with unpolarised double and\u0000triple-zeta basis sets (like 6-31G and 6-311G) having very poor performance.\u0000Appropriate use of polarisation functions (e.g. 6-31G*) is essential to obtain\u0000the accuracy offered by double or triple zeta basis sets. In our study, the\u0000best performance in our study for double and triple zeta basis set are\u00006-31++G** and pcseg-2 respectively. The polarised 6-311G basis set family has\u0000poor parameterisation which means its performance is more like a double-zeta\u0000than triple-zeta basis set. All versions of the 6-311G basis set family should\u0000be avoided entirely for valence chemistry calculations moving forward.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"401 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Lozano-Martín, David Vega-Maza, Alejandro Moreau, M. Carmen Martín, Dirk Tuma, José J. Segovia
This work aims to address the technical aspects related to the thermodynamic characterization of natural gas mixtures blended with hydrogen for the introduction of alternative energy sources within the Power-to-Gas framework. For that purpose, new experimental speed of sound data are presented in the pressure range between (0.1 up to 13) MPa and at temperatures of (260, 273.16, 300, 325, and 350) K for two mixtures qualified as primary calibration standards: a 11 component synthetic natural gas mixture (11 M), and another low-calorific $H_{2}$-enriched natural gas mixture with a nominal molar percentage $x_{H_{2}}$ = 3%. Measurements have been gathered using a spherical acoustic resonator with an experimental expanded ($k$ = 2) uncertainty better than 200 parts in $10^{6}$ (0.02%) in the speed of sound. The heat capacity ratio as perfect-gas $gamma_{pg}$, the molar heat capacity as perfect-gas $C_{p,m}^{pg}$, and the second $beta_{a}$ and third $gamma_{a}$ acoustic virial coefficients are derived from the speed of sound values. All the results are compared with the reference mixture models for natural gas-like mixtures, the AGA8-DC92 EoS and the GERG-2008 EoS, with special attention to the impact of hydrogen on those properties. Data are found to be mostly consistent within the model uncertainty in the 11 M synthetic mixture as expected, but for the hydrogen-enriched mixture in the limit of the model uncertainty at the highest measuring pressures.
{"title":"Speed of sound data, derived perfect-gas heat capacities, and acoustic virial coefficients of a calibration standard natural gas mixture and a low-calorific $H_{2}$-enriched mixture","authors":"Daniel Lozano-Martín, David Vega-Maza, Alejandro Moreau, M. Carmen Martín, Dirk Tuma, José J. Segovia","doi":"arxiv-2409.04094","DOIUrl":"https://doi.org/arxiv-2409.04094","url":null,"abstract":"This work aims to address the technical aspects related to the thermodynamic\u0000characterization of natural gas mixtures blended with hydrogen for the\u0000introduction of alternative energy sources within the Power-to-Gas framework.\u0000For that purpose, new experimental speed of sound data are presented in the\u0000pressure range between (0.1 up to 13) MPa and at temperatures of (260, 273.16,\u0000300, 325, and 350) K for two mixtures qualified as primary calibration\u0000standards: a 11 component synthetic natural gas mixture (11 M), and another\u0000low-calorific $H_{2}$-enriched natural gas mixture with a nominal molar\u0000percentage $x_{H_{2}}$ = 3%. Measurements have been gathered using a spherical\u0000acoustic resonator with an experimental expanded ($k$ = 2) uncertainty better\u0000than 200 parts in $10^{6}$ (0.02%) in the speed of sound. The heat capacity\u0000ratio as perfect-gas $gamma_{pg}$, the molar heat capacity as perfect-gas\u0000$C_{p,m}^{pg}$, and the second $beta_{a}$ and third $gamma_{a}$ acoustic\u0000virial coefficients are derived from the speed of sound values. All the results\u0000are compared with the reference mixture models for natural gas-like mixtures,\u0000the AGA8-DC92 EoS and the GERG-2008 EoS, with special attention to the impact\u0000of hydrogen on those properties. Data are found to be mostly consistent within\u0000the model uncertainty in the 11 M synthetic mixture as expected, but for the\u0000hydrogen-enriched mixture in the limit of the model uncertainty at the highest\u0000measuring pressures.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Lozano-Martín, Alejandro Moreau, César R. Chamorro
The accurate knowledge of the thermophysical and thermodynamic properties of pure hydrogen and hydrogen mixtures plays an important role in the design and operation of many processes involved in hydrogen production, transport, storage, and use. These data are needed for the development of theoretical models necessary for the introduction of hydrogen as a promising energy carrier in the near future. A literature survey on both the available experimental data and the theoretical models associated with the thermodynamic properties of hydrogen mixtures, within the operational ranges of industrial interest for composition, temperature, and pressure, is presented in this work. Considering the available experimental data and the requirements for the design and operation of hydrogen systems, the most relevant gaps in temperature, pressure and composition are identified.
{"title":"Thermophysical properties of hydrogen mixtures relevant for the development of the hydrogen economy: Review of available experimental data and thermodynamic models","authors":"Daniel Lozano-Martín, Alejandro Moreau, César R. Chamorro","doi":"arxiv-2409.03666","DOIUrl":"https://doi.org/arxiv-2409.03666","url":null,"abstract":"The accurate knowledge of the thermophysical and thermodynamic properties of\u0000pure hydrogen and hydrogen mixtures plays an important role in the design and\u0000operation of many processes involved in hydrogen production, transport,\u0000storage, and use. These data are needed for the development of theoretical\u0000models necessary for the introduction of hydrogen as a promising energy carrier\u0000in the near future. A literature survey on both the available experimental data\u0000and the theoretical models associated with the thermodynamic properties of\u0000hydrogen mixtures, within the operational ranges of industrial interest for\u0000composition, temperature, and pressure, is presented in this work. Considering\u0000the available experimental data and the requirements for the design and\u0000operation of hydrogen systems, the most relevant gaps in temperature, pressure\u0000and composition are identified.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Lozano-Martín, Peyman Khanipour, Heinrich Kipphardt, Dirk Tuma, César R. Chamorro
For the gradual introduction of hydrogen in the energy market, the study of the properties of mixtures of hydrogen with typical components of natural gas (NG) and liquefied petroleum gas (LPG) is of great importance. This work aims to provide accurate experimental ($p$, $rho$, $T$) data for three hydrogen-propane mixtures with nominal compositions (amount of substance, mol/mol) of (0.95$H_{2}$ + 0.05$C_{3}H_{8}$), (0.90$H_{2}$ + 0.10$C_{3}H_{8}$), and (0.83$H_{2}$ + 0.17$C_{3}H_{8}$), at temperatures of 250, 275, 300, 325, 350, and 375 K, and pressures up to 20 MPa. A single-sinker densimeter was used to determine the density of the mixtures. Experimental density data were compared to the densities calculated from two reference equations of state: the GERG-2008 and the AGA8-DC92. Relative deviations from the GERG-2008 EoS are systematically larger than those from the AGA8-DC92. They are within the $pm$0.5% band for the mixture with 5% of propane, but deviations are higher than 0.5% for the mixtures with 10% and 17% of propane, especially at low temperatures and high pressures. Finally, the sets of new experimental data have been processed by the application of two different statistical equations of state: the virial equation of state, through the second and third virial coefficients, $B$($T$, $x$) and $C$($T$, $x$), and the PC-SAFT equation of state.
{"title":"Thermodynamic characterization of the ($H_{2}$ + $C_{3}H_{8}$) system significant for the hydrogen economy: Experimental ($p$, $ρ$, $T$) determination and equation-of-state modelling","authors":"Daniel Lozano-Martín, Peyman Khanipour, Heinrich Kipphardt, Dirk Tuma, César R. Chamorro","doi":"arxiv-2409.03647","DOIUrl":"https://doi.org/arxiv-2409.03647","url":null,"abstract":"For the gradual introduction of hydrogen in the energy market, the study of\u0000the properties of mixtures of hydrogen with typical components of natural gas\u0000(NG) and liquefied petroleum gas (LPG) is of great importance. This work aims\u0000to provide accurate experimental ($p$, $rho$, $T$) data for three\u0000hydrogen-propane mixtures with nominal compositions (amount of substance,\u0000mol/mol) of (0.95$H_{2}$ + 0.05$C_{3}H_{8}$), (0.90$H_{2}$ + 0.10$C_{3}H_{8}$),\u0000and (0.83$H_{2}$ + 0.17$C_{3}H_{8}$), at temperatures of 250, 275, 300, 325,\u0000350, and 375 K, and pressures up to 20 MPa. A single-sinker densimeter was used\u0000to determine the density of the mixtures. Experimental density data were\u0000compared to the densities calculated from two reference equations of state: the\u0000GERG-2008 and the AGA8-DC92. Relative deviations from the GERG-2008 EoS are\u0000systematically larger than those from the AGA8-DC92. They are within the\u0000$pm$0.5% band for the mixture with 5% of propane, but deviations are higher\u0000than 0.5% for the mixtures with 10% and 17% of propane, especially at low\u0000temperatures and high pressures. Finally, the sets of new experimental data\u0000have been processed by the application of two different statistical equations\u0000of state: the virial equation of state, through the second and third virial\u0000coefficients, $B$($T$, $x$) and $C$($T$, $x$), and the PC-SAFT equation of\u0000state.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Weike Quan, Zihao Wang, Yueqing Shi, Kangkai Liang, Liya Bi, Hao Zhou, Zhiyuan Yin, Wanlu Li, Shaowei Li
On-demand control of molecular actions is a crucial step toward the realization of single-molecule functional devices. Such a control can be achieved by manipulating interactions between individual molecules and their nanoscale environment. In this study, we induce and manipulate the conformational transition of a single molecular adsorbate by exciting its vibrations with tunneling electrons using scanning tunneling microscopy. Several transition pathways between two structural states of a pyrrolidine molecule on a Cu(100) surface have been identified as being driven by different molecular vibrations. Density functional theory simulations further determine the nuclear motions of these vibrational modes. The introduction of tip-induced van der Waals forces and intermolecular interactions allows for precise manipulation of the molecule-environment interaction, which shifts the vibrational energies and alters the transition probability through different channels between the two structural states. This work reveals how molecular conformational transitions can be modulated by external force fields in a tunable nano-cavity, highlighting the potential to deliberately engineer molecule-environment interactions for specific molecular functions.
{"title":"Nano-Scale Manipulation of Single-Molecule Conformational Transition Through Vibrational Excitation","authors":"Weike Quan, Zihao Wang, Yueqing Shi, Kangkai Liang, Liya Bi, Hao Zhou, Zhiyuan Yin, Wanlu Li, Shaowei Li","doi":"arxiv-2409.03195","DOIUrl":"https://doi.org/arxiv-2409.03195","url":null,"abstract":"On-demand control of molecular actions is a crucial step toward the\u0000realization of single-molecule functional devices. Such a control can be\u0000achieved by manipulating interactions between individual molecules and their\u0000nanoscale environment. In this study, we induce and manipulate the\u0000conformational transition of a single molecular adsorbate by exciting its\u0000vibrations with tunneling electrons using scanning tunneling microscopy.\u0000Several transition pathways between two structural states of a pyrrolidine\u0000molecule on a Cu(100) surface have been identified as being driven by different\u0000molecular vibrations. Density functional theory simulations further determine\u0000the nuclear motions of these vibrational modes. The introduction of tip-induced\u0000van der Waals forces and intermolecular interactions allows for precise\u0000manipulation of the molecule-environment interaction, which shifts the\u0000vibrational energies and alters the transition probability through different\u0000channels between the two structural states. This work reveals how molecular\u0000conformational transitions can be modulated by external force fields in a\u0000tunable nano-cavity, highlighting the potential to deliberately engineer\u0000molecule-environment interactions for specific molecular functions.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
José J. Segovia, Daniel Lozano-Martín, Dirk Tuma, Alejandro Moreau, M. Carmen Martín, David Vega-Maza
This work aims to address the technical concerns related to the thermodynamic characterization of gas mixtures blended with hydrogen for the implementation of hydrogen as a new energy vector. For this purpose, new experimental speed of sound measurements have been done in gaseous and supercritical phases of two binary mixtures of nitrogen and hydrogen using the most accurate technique available, i.e., the spherical acoustic resonator, yielding an experimental expanded ($k$ = 2) uncertainty of only 220 parts in $10^{6}$ (0.022%). The measurements cover the pressure range between (0.5 and 20) MPa, the temperature range between (260 and 350) K, and the composition range with a nominal mole percentage of hydrogen of (5 and 10) mol%, respectively. From the speed of sound data sets, thermophysical properties that are relevant for the characterization of the mixture, namely the second $beta_{a}$ and third $gamma_{a}$ acoustic virial coefficients, are derived. These results are thoroughly compared and discussed with the established reference mixture models valid for mixtures of nitrogen and hydrogen, such as the AGA8-DC92 EoS, the GERG-2008 EoS, and the recently developed adaptation of the GERG-2008 EoS, here denoted GERG-$H_{2}$_improved EoS. Special attention has been given to the effect of hydrogen concentration on those properties, showing that only the GERG-$H_{2}$_improved EoS is consistent with the data sets within the experimental uncertainty in most measuring conditions.
{"title":"Speed of sound data and acoustic virial coefficients of two binary ($N_{2}$ + $H_{2}$) mixtures at temperatures between (260 and 350) K and at pressures between (0.5 and 20) MPa","authors":"José J. Segovia, Daniel Lozano-Martín, Dirk Tuma, Alejandro Moreau, M. Carmen Martín, David Vega-Maza","doi":"arxiv-2409.03677","DOIUrl":"https://doi.org/arxiv-2409.03677","url":null,"abstract":"This work aims to address the technical concerns related to the thermodynamic\u0000characterization of gas mixtures blended with hydrogen for the implementation\u0000of hydrogen as a new energy vector. For this purpose, new experimental speed of\u0000sound measurements have been done in gaseous and supercritical phases of two\u0000binary mixtures of nitrogen and hydrogen using the most accurate technique\u0000available, i.e., the spherical acoustic resonator, yielding an experimental\u0000expanded ($k$ = 2) uncertainty of only 220 parts in $10^{6}$ (0.022%). The\u0000measurements cover the pressure range between (0.5 and 20) MPa, the temperature\u0000range between (260 and 350) K, and the composition range with a nominal mole\u0000percentage of hydrogen of (5 and 10) mol%, respectively. From the speed of\u0000sound data sets, thermophysical properties that are relevant for the\u0000characterization of the mixture, namely the second $beta_{a}$ and third\u0000$gamma_{a}$ acoustic virial coefficients, are derived. These results are\u0000thoroughly compared and discussed with the established reference mixture models\u0000valid for mixtures of nitrogen and hydrogen, such as the AGA8-DC92 EoS, the\u0000GERG-2008 EoS, and the recently developed adaptation of the GERG-2008 EoS, here\u0000denoted GERG-$H_{2}$_improved EoS. Special attention has been given to the\u0000effect of hydrogen concentration on those properties, showing that only the\u0000GERG-$H_{2}$_improved EoS is consistent with the data sets within the\u0000experimental uncertainty in most measuring conditions.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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