The effective attenuation length (EAL) is a useful parameter in quantitative applications of x-ray photoelectron spectroscopy (XPS). This parameter is used in place of the inelastic mean free path (IMFP) in expressions for different XPS applications to correct those expressions for elastic scattering of the photoelectrons. We consider expressions used to determine (i) the thickness of an overlayer film on a planar substrate, (ii) the surface composition, (iii) the depth of a thin marker or delta layer, and (iv) the shell thickness of a core–shell nanoparticle. An EAL can be used for each of these applications. In general, the EAL depends on the particular defining equation as well as on the XPS configuration. Many attempts were made in the 1970s and 1980s to measure EALs for the determination of overlayer-film thicknesses, but there were often wide scatters in the reported results due to the difficulty in preparing uniform films with known thicknesses. We have therefore been motivated to calculate EALs for each application. The SRD 82 database from the National Institute of Standards and Technology (NIST) provides EALs for the measurement of overlayer-film thicknesses and of marker-layer depths. These EALs can be determined for photoelectron energies between 50 eV and 2 keV and for user-specified XPS configurations. We review EAL predictive equations for the determination of overlayer-film thicknesses on a planar substrate for XPS with unpolarized x rays and with linearly polarized x rays as well as an EAL predictive equation for quantitative analysis by XPS. These equations are simple analytical expressions that are valid for well-defined ranges of experimental conditions and for useful ranges of electron energies. We also point out that EALs for the determination of overlayer-film thicknesses can be derived from the simulated photoelectron intensities obtained from the NIST Database for the Simulation of Electron Spectra for Surface Analysis (SRD 100). Where possible, we make comparisons of the calculated EALs with illustrative experimental results. A key parameter in the EAL predictive equations is the so-called albedo, a useful measure of the strength of elastic-scattering effects in a material. The albedo is a simple function of the IMFP and the transport mean free path (TRMFP). We provide a tabulation of albedo and TRMFP values in the supplementary material for 41 elemental solids and 42 inorganic compounds for photoelectron energies between 50 eV and 30 keV. For other materials, albedo values can be determined from IMFP and TRMFP data available in the NIST SRD 82 and SRD 100 databases.
{"title":"Effective Attenuation Lengths for Different Quantitative Applications of X-ray Photoelectron Spectroscopy","authors":"A. Jablonski, C. Powell","doi":"10.1063/5.0008576","DOIUrl":"https://doi.org/10.1063/5.0008576","url":null,"abstract":"The effective attenuation length (EAL) is a useful parameter in quantitative applications of x-ray photoelectron spectroscopy (XPS). This parameter is used in place of the inelastic mean free path (IMFP) in expressions for different XPS applications to correct those expressions for elastic scattering of the photoelectrons. We consider expressions used to determine (i) the thickness of an overlayer film on a planar substrate, (ii) the surface composition, (iii) the depth of a thin marker or delta layer, and (iv) the shell thickness of a core–shell nanoparticle. An EAL can be used for each of these applications. In general, the EAL depends on the particular defining equation as well as on the XPS configuration. Many attempts were made in the 1970s and 1980s to measure EALs for the determination of overlayer-film thicknesses, but there were often wide scatters in the reported results due to the difficulty in preparing uniform films with known thicknesses. We have therefore been motivated to calculate EALs for each application. The SRD 82 database from the National Institute of Standards and Technology (NIST) provides EALs for the measurement of overlayer-film thicknesses and of marker-layer depths. These EALs can be determined for photoelectron energies between 50 eV and 2 keV and for user-specified XPS configurations. We review EAL predictive equations for the determination of overlayer-film thicknesses on a planar substrate for XPS with unpolarized x rays and with linearly polarized x rays as well as an EAL predictive equation for quantitative analysis by XPS. These equations are simple analytical expressions that are valid for well-defined ranges of experimental conditions and for useful ranges of electron energies. We also point out that EALs for the determination of overlayer-film thicknesses can be derived from the simulated photoelectron intensities obtained from the NIST Database for the Simulation of Electron Spectra for Surface Analysis (SRD 100). Where possible, we make comparisons of the calculated EALs with illustrative experimental results. A key parameter in the EAL predictive equations is the so-called albedo, a useful measure of the strength of elastic-scattering effects in a material. The albedo is a simple function of the IMFP and the transport mean free path (TRMFP). We provide a tabulation of albedo and TRMFP values in the supplementary material for 41 elemental solids and 42 inorganic compounds for photoelectron energies between 50 eV and 30 keV. For other materials, albedo values can be determined from IMFP and TRMFP data available in the NIST SRD 82 and SRD 100 databases.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/5.0008576","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44234201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Furtenbacher, Roland Tóbiás, J. Tennyson, O. Polyansky, A. Császár
A detailed understanding of the complex rotation–vibration spectrum of the water molecule is vital for many areas of scientific and human activity, and thus, it is well studied in a number of spectral regions. To enhance our perception of the spectrum of the parent water isotopologue, H216O, a dataset of 270 745 non-redundant measured transitions is assembled, analyzed, and validated, yielding 19 204 rovibrational energy levels with statistically reliable uncertainties. The present study extends considerably an analysis of the rovibrational spectrum of H216O, published in 2013, by employing an improved methodology, considering about one-third more new observations (often with greatly decreased uncertainties), and using a highly accurate first-principles energy list for validation purposes. The database of experimental rovibrational transitions and empirical energy levels of H216O created during this study is called W2020. Some of the new transitions in W2020 allow the improved treatment of many parts of the dataset, especially considering the uncertainties of the experimental line positions and the empirical energy values. The W2020 dataset is examined to assess where measurements are still lacking even for this most thoroughly studied isotopologue of water, and to provide definitive energies for the lower and upper states of many yet-to-be-measured transitions. The W2020 dataset allows the evaluation of several previous compilations of spectroscopic data of water and the accuracy of previous effective Hamiltonian fits.
{"title":"W2020: A Database of Validated Rovibrational Experimental Transitions and Empirical Energy Levels of H216O","authors":"T. Furtenbacher, Roland Tóbiás, J. Tennyson, O. Polyansky, A. Császár","doi":"10.1063/5.0008253","DOIUrl":"https://doi.org/10.1063/5.0008253","url":null,"abstract":"A detailed understanding of the complex rotation–vibration spectrum of the water molecule is vital for many areas of scientific and human activity, and thus, it is well studied in a number of spectral regions. To enhance our perception of the spectrum of the parent water isotopologue, H216O, a dataset of 270 745 non-redundant measured transitions is assembled, analyzed, and validated, yielding 19 204 rovibrational energy levels with statistically reliable uncertainties. The present study extends considerably an analysis of the rovibrational spectrum of H216O, published in 2013, by employing an improved methodology, considering about one-third more new observations (often with greatly decreased uncertainties), and using a highly accurate first-principles energy list for validation purposes. The database of experimental rovibrational transitions and empirical energy levels of H216O created during this study is called W2020. Some of the new transitions in W2020 allow the improved treatment of many parts of the dataset, especially considering the uncertainties of the experimental line positions and the empirical energy values. The W2020 dataset is examined to assess where measurements are still lacking even for this most thoroughly studied isotopologue of water, and to provide definitive energies for the lower and upper states of many yet-to-be-measured transitions. The W2020 dataset allows the evaluation of several previous compilations of spectroscopic data of water and the accuracy of previous effective Hamiltonian fits.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"49 1","pages":"033101"},"PeriodicalIF":4.3,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/5.0008253","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49118783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this work is to present a unified collection of structural and chemical information on a series of neutral chemical tri-elemental species up to a molecular formula C2H2O8, which may be used for validation purposes, for deep structured learning or indeed more simply for basic data of a single species. Such a collection vastly is tightly focused in terms of its component parts, contains novel results, and covers a number of chemical classes including stable molecules, radicals, carbenes, dipolar species, and excited states. Wherever possible, comparisons are made to the experimental and quantum chemical literature of gas-phase molecules, but the paucity of such means that there is only a very limited scope for validation. The primary data consist of structural information in the form of Cartesian coordinates, rotational constants together with vibrational frequencies, and anharmonicity coefficients, all obtained through density functional, B3LYP, calculations with the cc-pVTZ+d basis set. Standard statistical thermodynamic relations are then used to compute entropy, specific heat at constant pressure, and an enthalpy function over temperatures from 298.15 K to 2000 K. Supplementary material contains all the information necessary to carry out these calculations over different conditions as required as well as the raw species data. High-level quantum mechanical computations employing composite model chemistries, including CBS-QB3, CBS-APNO, G3, G4, W1BD, WMS, W2X, and W3X-L, are used to derive formation enthalpies via atomization and/or isodesmic calculations as appropriate.
{"title":"An Organized Collection of Theoretical Gas-Phase Geometric, Spectroscopic, and Thermochemical Data of Oxygenated Hydrocarbons, CxHyOz (x, y = 1, 2; z = 1–8), of Relevance to Atmospheric, Astrochemical, and Combustion Sciences","authors":"J. Simmie, J. Würmel","doi":"10.1063/1.5132628","DOIUrl":"https://doi.org/10.1063/1.5132628","url":null,"abstract":"The objective of this work is to present a unified collection of structural and chemical information on a series of neutral chemical tri-elemental species up to a molecular formula C2H2O8, which may be used for validation purposes, for deep structured learning or indeed more simply for basic data of a single species. Such a collection vastly is tightly focused in terms of its component parts, contains novel results, and covers a number of chemical classes including stable molecules, radicals, carbenes, dipolar species, and excited states. Wherever possible, comparisons are made to the experimental and quantum chemical literature of gas-phase molecules, but the paucity of such means that there is only a very limited scope for validation. The primary data consist of structural information in the form of Cartesian coordinates, rotational constants together with vibrational frequencies, and anharmonicity coefficients, all obtained through density functional, B3LYP, calculations with the cc-pVTZ+d basis set. Standard statistical thermodynamic relations are then used to compute entropy, specific heat at constant pressure, and an enthalpy function over temperatures from 298.15 K to 2000 K. Supplementary material contains all the information necessary to carry out these calculations over different conditions as required as well as the raw species data. High-level quantum mechanical computations employing composite model chemistries, including CBS-QB3, CBS-APNO, G3, G4, W1BD, WMS, W2X, and W3X-L, are used to derive formation enthalpies via atomization and/or isodesmic calculations as appropriate.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"1 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2020-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5132628","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43302177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Tkaczuk, I. Bell, E. Lemmon, N. Luchier, F. Millet
Based on the conceptual design reports for the Future Circular Collider cryogenic system, the need for more accurate thermodynamic property models of cryogenic mixtures of noble gases was identified. Both academic institutes and industries have identified the lack of a reliable equation of state for mixtures used at very low temperatures. Detailed cryogenic architecture modeling and design cannot be carried out without accurate fluid properties. Therefore, the helium–neon equation was the first goal of this work, and it was further extended to other fluids beneficial for scientific and industrial applications beyond the particle physics needs. The properties of the noble gas mixtures of helium–neon, neon–argon, and helium–argon are accurately modeled with the equations of state explicit in the Helmholtz energy.
{"title":"Equations of State for the Thermodynamic Properties of Binary Mixtures for Helium-4, Neon, and Argon","authors":"J. Tkaczuk, I. Bell, E. Lemmon, N. Luchier, F. Millet","doi":"10.1063/1.5142275","DOIUrl":"https://doi.org/10.1063/1.5142275","url":null,"abstract":"Based on the conceptual design reports for the Future Circular Collider cryogenic system, the need for more accurate thermodynamic property models of cryogenic mixtures of noble gases was identified. Both academic institutes and industries have identified the lack of a reliable equation of state for mixtures used at very low temperatures. Detailed cryogenic architecture modeling and design cannot be carried out without accurate fluid properties. Therefore, the helium–neon equation was the first goal of this work, and it was further extended to other fluids beneficial for scientific and industrial applications beyond the particle physics needs. The properties of the noble gas mixtures of helium–neon, neon–argon, and helium–argon are accurately modeled with the equations of state explicit in the Helmholtz energy.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"49 1","pages":"023101"},"PeriodicalIF":4.3,"publicationDate":"2020-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5142275","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41337019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiong Xiao, D. Rowland, Saif Z. S. Al Ghafri, E. May
{"title":"Publisher’s Note: “Wide-Ranging Reference Correlations for Dilute Gas Transport Properties Based on Ab Initio Calculations and Viscosity Ratio Measurements” [J. Phys. Chem. Ref. Data 49, 013101 (2020)]","authors":"Xiong Xiao, D. Rowland, Saif Z. S. Al Ghafri, E. May","doi":"10.1063/5.0004137","DOIUrl":"https://doi.org/10.1063/5.0004137","url":null,"abstract":"","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"49 1","pages":"029901"},"PeriodicalIF":4.3,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/5.0004137","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46718745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. McEachran, B. Marinković, G. García, R. White, P. Stokes, D. B. Jones, M. Brunger
We report results from the application of our optical potential and relativistic optical potential methods to electron–zinc scattering. The energy range of this study was 0.01–5000 eV, with origina...
{"title":"Integral Cross Sections for Electron–Zinc Scattering over a Broad Energy Range (0.01–5000 eV)","authors":"R. McEachran, B. Marinković, G. García, R. White, P. Stokes, D. B. Jones, M. Brunger","doi":"10.1063/1.5135573","DOIUrl":"https://doi.org/10.1063/1.5135573","url":null,"abstract":"We report results from the application of our optical potential and relativistic optical potential methods to electron–zinc scattering. The energy range of this study was 0.01–5000 eV, with origina...","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"49 1","pages":"013102"},"PeriodicalIF":4.3,"publicationDate":"2020-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5135573","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43881001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The combined use of experimental viscosity ratios together with ab initio calculations for helium has driven significant improvements in the description of dilute gas transport properties. Here, we first use improvements made to ab initio helium calculations to update viscosity ratios measured for H2, Ar, CH4, and Xe by May et al. [Int. J. Thermophys. 28, 1085 (2007)] over the temperature range of 200–400 K, reducing the uncertainties of the data to 0.055%, 0.038%, 0.067%, and 0.084%, respectively. Separately, we extend the technique of combining viscosity ratios with ab initio calculations to develop new reference correlations for the dilute gas viscosity of 10 gases: helium, neon, argon, krypton, xenon, hydrogen, nitrogen, methane, ethane, and propane. This is achieved by combining the ratios of viscosities calculated ab initio at the target temperature and at 298.15 K with experimentally based reference viscosity values for each gas at 298.15 K. The new reference dilute gas viscosity correlations span temperature ranges from at least 150 K to 1200 K with relative uncertainties between 30% (krypton) and 85% (methane) lower than the original ab initio results. For the noble gases, ab initio calculations for the Prandtl number are used to develop reference correlations for thermal conductivity ranging from at least 100 K to 5000 K, with relative uncertainties ranging from 0.04% (argon) to 0.20% (xenon). The new reference correlations are compared with available experimental data at dilute gas conditions. In general, the data agree with the new correlations within the claimed experimental uncertainty.
{"title":"Wide-Ranging Reference Correlations for Dilute Gas Transport Properties Based on Ab Initio Calculations and Viscosity Ratio Measurements","authors":"D. Rowland, Saif Z. S. Al Ghafri, E. May","doi":"10.1063/1.5125100","DOIUrl":"https://doi.org/10.1063/1.5125100","url":null,"abstract":"The combined use of experimental viscosity ratios together with ab initio calculations for helium has driven significant improvements in the description of dilute gas transport properties. Here, we first use improvements made to ab initio helium calculations to update viscosity ratios measured for H2, Ar, CH4, and Xe by May et al. [Int. J. Thermophys. 28, 1085 (2007)] over the temperature range of 200–400 K, reducing the uncertainties of the data to 0.055%, 0.038%, 0.067%, and 0.084%, respectively. Separately, we extend the technique of combining viscosity ratios with ab initio calculations to develop new reference correlations for the dilute gas viscosity of 10 gases: helium, neon, argon, krypton, xenon, hydrogen, nitrogen, methane, ethane, and propane. This is achieved by combining the ratios of viscosities calculated ab initio at the target temperature and at 298.15 K with experimentally based reference viscosity values for each gas at 298.15 K. The new reference dilute gas viscosity correlations span temperature ranges from at least 150 K to 1200 K with relative uncertainties between 30% (krypton) and 85% (methane) lower than the original ab initio results. For the noble gases, ab initio calculations for the Prandtl number are used to develop reference correlations for thermal conductivity ranging from at least 100 K to 5000 K, with relative uncertainties ranging from 0.04% (argon) to 0.20% (xenon). The new reference correlations are compared with available experimental data at dilute gas conditions. In general, the data agree with the new correlations within the claimed experimental uncertainty.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"49 1","pages":"013101"},"PeriodicalIF":4.3,"publicationDate":"2020-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5125100","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49415007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mi-Young Song, J. Yoon, Hyuck Cho, G. Karwasz, V. Kokoouline, Yoshiharu Nakamura, J. Tennyson
Cross section data are compiled from the literature for electron collisions with oxides of nitrogen (NxOy) molecules: the species nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2) are explicitly considered. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, and dissociative attachment. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed up to the end of 2017. These results are supplemented by a reanalysis of the swarm measurements for NO and newly calculated cross sections for rotational excitation of N2O and for rotational excitation and electronic excitation of NO2.Cross section data are compiled from the literature for electron collisions with oxides of nitrogen (NxOy) molecules: the species nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2) are explicitly considered. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, and dissociative attachment. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed up to the end of 2017. These results are supplemented by a reanalysis of the swarm measurements for NO and newly calculated cross sections for rotational excitation of N2O and for rotational excitation and electronic excitation of NO2.
{"title":"Cross Sections for Electron Collisions with NO, N2O, and NO2","authors":"Mi-Young Song, J. Yoon, Hyuck Cho, G. Karwasz, V. Kokoouline, Yoshiharu Nakamura, J. Tennyson","doi":"10.1063/1.5114722","DOIUrl":"https://doi.org/10.1063/1.5114722","url":null,"abstract":"Cross section data are compiled from the literature for electron collisions with oxides of nitrogen (NxOy) molecules: the species nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2) are explicitly considered. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, and dissociative attachment. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed up to the end of 2017. These results are supplemented by a reanalysis of the swarm measurements for NO and newly calculated cross sections for rotational excitation of N2O and for rotational excitation and electronic excitation of NO2.Cross section data are compiled from the literature for electron collisions with oxides of nitrogen (NxOy) molecules: the species nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2) are explicitly considered. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, and dissociative attachment. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed up to the end of 2017. These results are supplemented by a reanalysis of the swarm measurements for NO and newly calculated cross sections for rotational excitation of N2O and for rotational excitation and electronic excitation of NO2.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"48 1","pages":"043104"},"PeriodicalIF":4.3,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5114722","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43067705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the commercial transfer of billions of cubic meters of natural gases, the knowledge of the gross calorific value (GCV) of the main natural gas components and, in particular, of methane, is of outstanding interest. On the basis of previous work carried out by a Groupe Europeen de Recherches Gazieres (GERG)–Physikalisch-Technische Bundesanstalt collaboration, the so-called GERG calorimeter was further developed on the hardware as well as on the software side. With the renewed GERG calorimeter, the GCV of CH4 could be determined with unprecedented precision and accuracy. Important elements for improving the measuring methodology of flame calorimetry included the in situ calibration of the mass of the burned gas, the determination of the actual exhaust gas temperatures, and the detection of the water input by countercurrent water absorption from ambient air. For the first time, it was possible to determine the GCV not only via direct online weighing of the mass of burned gas but also via the stoichiometric water balance with a consistency of about 3.5 ppm. Based on 27 weighings of the mass of burned gas, the real-gas GCV of methane is determined as Hs(CH4) = 890 202.1 J mol−1 with a confidence interval of ±52.6 J mol−1 (t95% = 2.056). This value is by ΔHs/Hs = (−0.0436 ± 0.0059)% below the real-gas GCV of Hs(CH4) = (890 590 ± 380) J mol−1 (k = 2) converted according to ISO 6976:2016. The difference can be explained by systematic influences as well as by failures in the stoichiometric water balance in all other measurements.Due to the commercial transfer of billions of cubic meters of natural gases, the knowledge of the gross calorific value (GCV) of the main natural gas components and, in particular, of methane, is of outstanding interest. On the basis of previous work carried out by a Groupe Europeen de Recherches Gazieres (GERG)–Physikalisch-Technische Bundesanstalt collaboration, the so-called GERG calorimeter was further developed on the hardware as well as on the software side. With the renewed GERG calorimeter, the GCV of CH4 could be determined with unprecedented precision and accuracy. Important elements for improving the measuring methodology of flame calorimetry included the in situ calibration of the mass of the burned gas, the determination of the actual exhaust gas temperatures, and the detection of the water input by countercurrent water absorption from ambient air. For the first time, it was possible to determine the GCV not only via direct online weighing of the mass of burned gas but also via the stoichiome...
{"title":"Accurate Measurements of the Gross Calorific Value of Methane by the Renewed GERG Calorimeter","authors":"N. Kurzeja, R. Span","doi":"10.1063/1.5110054","DOIUrl":"https://doi.org/10.1063/1.5110054","url":null,"abstract":"Due to the commercial transfer of billions of cubic meters of natural gases, the knowledge of the gross calorific value (GCV) of the main natural gas components and, in particular, of methane, is of outstanding interest. On the basis of previous work carried out by a Groupe Europeen de Recherches Gazieres (GERG)–Physikalisch-Technische Bundesanstalt collaboration, the so-called GERG calorimeter was further developed on the hardware as well as on the software side. With the renewed GERG calorimeter, the GCV of CH4 could be determined with unprecedented precision and accuracy. Important elements for improving the measuring methodology of flame calorimetry included the in situ calibration of the mass of the burned gas, the determination of the actual exhaust gas temperatures, and the detection of the water input by countercurrent water absorption from ambient air. For the first time, it was possible to determine the GCV not only via direct online weighing of the mass of burned gas but also via the stoichiometric water balance with a consistency of about 3.5 ppm. Based on 27 weighings of the mass of burned gas, the real-gas GCV of methane is determined as Hs(CH4) = 890 202.1 J mol−1 with a confidence interval of ±52.6 J mol−1 (t95% = 2.056). This value is by ΔHs/Hs = (−0.0436 ± 0.0059)% below the real-gas GCV of Hs(CH4) = (890 590 ± 380) J mol−1 (k = 2) converted according to ISO 6976:2016. The difference can be explained by systematic influences as well as by failures in the stoichiometric water balance in all other measurements.Due to the commercial transfer of billions of cubic meters of natural gases, the knowledge of the gross calorific value (GCV) of the main natural gas components and, in particular, of methane, is of outstanding interest. On the basis of previous work carried out by a Groupe Europeen de Recherches Gazieres (GERG)–Physikalisch-Technische Bundesanstalt collaboration, the so-called GERG calorimeter was further developed on the hardware as well as on the software side. With the renewed GERG calorimeter, the GCV of CH4 could be determined with unprecedented precision and accuracy. Important elements for improving the measuring methodology of flame calorimetry included the in situ calibration of the mass of the burned gas, the determination of the actual exhaust gas temperatures, and the detection of the water input by countercurrent water absorption from ambient air. For the first time, it was possible to determine the GCV not only via direct online weighing of the mass of burned gas but also via the stoichiome...","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"48 1","pages":"043103"},"PeriodicalIF":4.3,"publicationDate":"2019-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5110054","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48679323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Autumn D Zuckerman, Alicia Carver, Katrina Cooper, Brandon Markley, Amy Mitchell, Victoria W Reynolds, Marci Saknini, Houston Wyatt, Tara Kelley
Adherence and persistence to specialty medications are necessary to achieve successful outcomes of costly therapies. The increasing use of specialty medications has exposed several unique barriers to certain specialty treatments' continuation. Integrated specialty pharmacy teams facilitate transitions in sites of care, between different provider types, among prescribed specialty medications, and during financial coverage changes. We review obstacles encountered within these types of transitions and the role of the specialty pharmacist in overcoming these obstacles. Case examples for each type of specialty transition provide insight into the unique complexities faced by patients, and shed light on pharmacists' vital role in patient care. This insightful and real-world experience is needed to facilitate best practices in specialty care, particularly in the growing number of health-system specialty pharmacies.
{"title":"An Integrated Health-System Specialty Pharmacy Model for Coordinating Transitions of Care: Specialty Medication Challenges and Specialty Pharmacist Opportunities.","authors":"Autumn D Zuckerman, Alicia Carver, Katrina Cooper, Brandon Markley, Amy Mitchell, Victoria W Reynolds, Marci Saknini, Houston Wyatt, Tara Kelley","doi":"10.3390/pharmacy7040163","DOIUrl":"10.3390/pharmacy7040163","url":null,"abstract":"<p><p>Adherence and persistence to specialty medications are necessary to achieve successful outcomes of costly therapies. The increasing use of specialty medications has exposed several unique barriers to certain specialty treatments' continuation. Integrated specialty pharmacy teams facilitate transitions in sites of care, between different provider types, among prescribed specialty medications, and during financial coverage changes. We review obstacles encountered within these types of transitions and the role of the specialty pharmacist in overcoming these obstacles. Case examples for each type of specialty transition provide insight into the unique complexities faced by patients, and shed light on pharmacists' vital role in patient care. This insightful and real-world experience is needed to facilitate best practices in specialty care, particularly in the growing number of health-system specialty pharmacies.</p>","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3390/pharmacy7040163","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81708536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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