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Top 20 Most Read Articles
April 2013
The 20 articles with the most full-text downloads during the month, in descending order.
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Erratum: Viscosity of water—new international formulation and its background J. Phys. Chem. Ref. Data 12, 403 (1983); http://dx.doi.org/10.1063/1.555683 (1 page)
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Physical Properties of Ionic Liquids: Database and Evaluation J. Phys. Chem. Ref. Data 35, 1475 (2006); http://dx.doi.org/10.1063/1.2204959 (43 pages) Online Publication Date: 10 October 2006
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A comprehensive database on physical properties of ionic liquids (ILs), which was collected from 109 kinds of literature sources in the period from 1984 through 2004, has been presented. There are 1680 pieces of data on the physical properties for 588 available ILs, from which 276 kinds of cations and 55 kinds of anions were extracted. In terms of the collected database, the structure-property relationship was evaluated. The correlation of melting points of two most common systems, disubstituted imidazolium tetrafluoroborate and disubstituted imidazolium hexafluorophosphate, was carried out using a quantitative structure-property relationship method.
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Critically Evaluated Thermochemical Properties of Polycyclic Aromatic Hydrocarbons J. Phys. Chem. Ref. Data 37, 1855 (2008); http://dx.doi.org/10.1063/1.2955570 (142 pages) Online Publication Date: 23 October 2008
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Experimental thermochemical properties of benzene, toluene, and 63 polycyclic aromatic hydrocarbons, published within the period 1878–2008 (over 350 references), are reported. Available experimental data for the enthalpies of combustion used to calculate enthalpies of formation in the condensed state, combined with sublimation, vaporization, and fusion enthalpies, are critically evaluated. Whenever possible, recommended values for these thermochemical properties and for the enthalpies of formation in the gas state at T = 298.15 K are provided.
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J. Phys. Chem. Ref. Data 42, 023101 (2013); http://dx.doi.org/10.1063/1.4794091 (9 pages) Online Publication Date: 1 April 2013
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This paper contains new, representative reference equations for the thermal conductivity of n-heptane. The equations are based in part upon a body of experimental data that have been critically assessed for internal consistency and for agreement with theory whenever possible. In the case of the dilute-gas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. The correlations are applicable for the temperature range from the triple point to 600 K and pressures up to 250 MPa. The overall uncertainty (considered to be estimates of a combined expanded uncertainty with a coverage factor of 2) of the proposed correlation is estimated, for pressures less than 250 MPa and temperatures less than 600 K, to be less than 4%. |
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Molecular structures of gas‐phase polyatomic molecules determined by spectroscopic methods J. Phys. Chem. Ref. Data 8, 619 (1979); http://dx.doi.org/10.1063/1.555605 (104 pages)
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Spectroscopic data related to the structures of polyatomic molecules in the gas phase have been reviewed, critically evaluated, and compiled. All reported bond distances and angles have been classified as equilibrium (re), average (rz), substitution (rs), or effective (ro) parameters, and have been given a quality rating which is a measure of the parameter uncertainty. The surveyed literature includes work from all of the areas of gas‐phase spectroscopy from which precise quantitative structural information can be derived. Introductory material includes definitions of the various types of parameters and a description of the evaluation procedure. |
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Announcement: Multimedia Capability Added to Journal of Physical and Chemical Reference Data J. Phys. Chem. Ref. Data 38, 97 (2009); http://dx.doi.org/10.1063/1.3099311 (1 page) Online Publication Date: 10 March 2009
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The Spectrum of Molecular Oxygen J. Phys. Chem. Ref. Data 1, 423 (1972); http://dx.doi.org/10.1063/1.3253101 (112 pages) Online Publication Date: 29 October 2009
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This is a critical review and compilation of the observed and predicted spectroscopic data on O2 and its ions O2−, O2+ and O22+ The ultraviolet, visible, infrared, Raman, microwave, and electron paramagnetic resonance spectra are included. Each electronic band system is discussed in detail, and tables of band origins and heads are given. The microwave and EPR data are also tabulated. Special subjects such as the dissociation energy of O2, perturbations, and predissociations are discussed. Potential energy curves are given, as well as f‐values, Franck‐Condon integrals, and other intensity factors. A summary table lists the molecular constants for all known electronic states of O2 and O2+ Electronic structure and theoretical calculations are also discussed. |
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New International Formulation for the Thermal Conductivity of H2O J. Phys. Chem. Ref. Data 41, 033102 (2012); http://dx.doi.org/10.1063/1.4738955 (23 pages) Online Publication Date: 23 August 2012
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The International Association for the Properties of Water and Steam (IAPWS) encouraged an extensive research effort to update the IAPS Formulation 1985 for the Thermal Conductivity of Ordinary Water Substance, leading to the adoption of a Release on the IAPWS Formulation 2011 for the Thermal Conductivity of Ordinary Water Substance. This paper describes the development and evaluation of the 2011 formulation, which provides a correlating equation for the thermal conductivity of water for fluid states from the melting temperature up to 1173 K and 1000 MPa with uncertainties from less than 1% to 6%, depending on the state point. |
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J. Phys. Chem. Ref. Data 17, 513 (1988); http://dx.doi.org/10.1063/1.555805 (374 pages)
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Kinetic data for the radicals H⋅ and ⋅OH in aqueous solution,and the corresponding radical anions, ⋅O− and eaq−, have been critically pulse radiolysis, flash photolysis and other methods. Rate constants for over 3500 reaction are tabulated, including reaction with molecules, ions and other radicals derived from inorganic and organic solutes. |
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The spectrum of molecular nitrogen J. Phys. Chem. Ref. Data 6, 113 (1977); http://dx.doi.org/10.1063/1.555546 (195 pages)
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This is a critical review and compilation of the observed and predicted spectroscopic data on the molecule N2 and its ions N2 −, N2 +, N2 2+, and the molecule N3. Each electronic band system is discussed in detail, and tables of band origins and heads are given. In addition to the gas phase electronic, electron and Raman spectra, there are also examined the spectra of condensed molecular nitrogen as well as the pressure‐ and field‐induced infrared and microwave absorption. Dissociation energy of N2, predissociations, and perturbations are discussed. Potential energy curves are given, as well as radiative lifetimes, f‐values, and Franck‐Condon integrals. Molecular constants are listed for the known electronic states. Electronic structure and theoretical calculations are reviewed. |
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Gaseous Diffusion Coefficients J. Phys. Chem. Ref. Data 1, 3 (1972); http://dx.doi.org/10.1063/1.3253094 (116 pages) Online Publication Date: 28 October 2009
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Diffusion coefficients of binary mixtures of dilute gases are comprehensively compiled, critically evaluated, and correlated by new semi‐empirical expressions. There are seventy‐four systems for which the data are sufficiently extensive, consistent and accurate to allow diffusion coefficients to be recommended with confidence. Deviation plots are given for most of these systems. Almost every gaseous diffusion coefficient which was experimentally determined and reported prior to 1970 can be obtained from the annotated bibliography and table of gas pairs. A detailed analysis of experimental methods is given, and intercomparison of their results helps establish reliability limits for the data, which depend strongly on temperature. Direct measurements are supplemented by calculations based on knowledge of intermolecular forces derived from independent sources—molecular beam scattering for high temperatures, and London dispersion constants for low temperatures. In addition, diffusion coefficients for several mixtures are obtained from experimental data on mixture viscosities and thermal diffusion factors. Combination of all these results gives diffusion coefficients over a very extensive temperature range, from very low temperatures to 10 000 K. All data are corrected for composition dependence and for quantum effects. New semi‐empirical equations are derived for making such corrections easily. |
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Wavelengths, Transition Probabilities, and Energy Levels for the Spectra of Sodium (Na I–Na XI) J. Phys. Chem. Ref. Data 37, 1659 (2008); http://dx.doi.org/10.1063/1.2943652 (105 pages) Online Publication Date: 10 September 2008
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Energy levels, with classifications and uncertainties, have been compiled for the spectra of the neutral atom and all positive ions of sodium (Z = 11). Wavelengths with classifications, intensities, and transition probabilities are also tabulated. In addition, ground states and ionization energies are listed. Where available, the hyperfine structure constants and the percentages of the leading components of the energy levels are included. For all ionization stages of sodium, at least some experimental data are available; however, for those for which only a few transitions have been measured, theoretical calculations or values obtained by isoelectronic fitting are reported. Similarly, theoretical or isoelectronically determined ionization energies are given when they are thought to be more accurate than the available experimental data would produce.
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J. Phys. Chem. Ref. Data 31, 387 (2002); http://dx.doi.org/10.1063/1.1461829 (149 pages) Online Publication Date: 7 June 2002
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In 1995, the International Association for the Properties of Water and Steam (IAPWS) adopted a new formulation called “The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use”, which we abbreviate to IAPWS-95 formulation or IAPWS-95 for short. This IAPWS-95 formulation replaces the previous formulation adopted in 1984. This work provides information on the selected experimental data of the thermodynamic properties of water used to develop the new formulation, but information is also given on newer data. The article presents all details of the IAPWS-95 formulation, which is in the form of a fundamental equation explicit in the Helmholtz free energy. The function for the residual part of the Helmholtz free energy was fitted to selected data for the following properties: (a) thermal properties of the single-phase region (pρT) and of the vapor–liquid phase boundary (pσρ′ρ″T), including the phase-equilibrium condition (Maxwell criterion), and (b) the caloric properties specific isochoric heat capacity, specific isobaric heat capacity, speed of sound, differences in the specific enthalpy and in the specific internal energy, Joule–Thomson coefficient, and isothermal throttling coefficient. By applying modern strategies for optimizing the functional form of the equation of state and for the simultaneous nonlinear fitting to the data of all mentioned properties, the resulting IAPWS-95 formulation covers a validity range for temperatures from the melting line (lowest temperature 251.2 K at 209.9 MPa) to 1273 K and pressures up to 1000 MPa. In this entire range of validity, IAPWS-95 represents even the most accurate data to within their experimental uncertainty. In the most important part of the liquid region, the estimated uncertainty of IAPWS-95 ranges from ±0.001% to ±0.02% in density, ±0.03% to ±0.2% in speed of sound, and ±0.1% in isobaric heat capacity. In the liquid region at ambient pressure, IAPWS-95 is extremely accurate in density (uncertainty ⩽±0.0001%) and in speed of sound (±0.005%). In a large part of the gas region the estimated uncertainty in density ranges from ±0.03% to ±0.05%, in speed of sound it amounts to ±0.15% and in isobaric heat capacity it is ±0.2%. In the critical region, IAPWS-95 represents not only the thermal properties very well but also the caloric properties in a reasonable way. Special interest has been focused on the extrapolation behavior of the new formulation. At least for the basic properties such as pressure and enthalpy, IAPWS-95 can be extrapolated up to extremely high pressures and temperatures. In addition to the IAPWS-95 formulation, independent equations for vapor pressure, the densities, and the most important caloric properties along the vapor–liquid phase boundary, and for the pressure on the melting and sublimation curve, are given. Moreover, a so-called gas equation for densities up to 55 kg m−3 is also included. Tables of the thermodynamic properties calculated from the IAPWS-95 formulation are listed in the Appendix. © 2002 American Institute of Physics. |
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J. Phys. Chem. Ref. Data 25, 1509 (1996); http://dx.doi.org/10.1063/1.555991 (88 pages)
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This work reviews the available data on thermodynamic properties of carbon dioxide and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy. The function for the residual part of the Helmholtz free energy was fitted to selected data of the following properties: (a) thermal properties of the single‐phase region (pρT) and (b) of the liquid‐vapor saturation curve (ps, ρ′, ρ″) including the Maxwell criterion, (c) speed of sound w and (d) specific isobaric heat capacity cp of the single phase region and of the saturation curve, (e) specific isochoric heat capacity cv, (f) specific enthalpy h, (g) specific internal energy u, and (h) Joule–Thomson coefficient μ. By applying modern strategies for the optimization of the mathematical form of the equation of state and for the simultaneous nonlinear fit to the data of all these properties, the resulting formulation is able to represent even the most accurate data to within their experimental uncertainty. In the technically most important region up to pressures of 30 MPa and up to temperatures of 523 K, the estimated uncertainty of the equation ranges from ±0.03% to ±0.05% in the density, ±0.03% to ±1% in the speed of sound, and ±0.15% to ±1.5% in the isobaric heat capacity. Special interest has been focused on the description of the critical region and the extrapolation behavior of the formulation. Without a complex coupling to a scaled equation of state, the new formulation yields a reasonable description even of the caloric properties in the immediate vicinity of the critical point. At least for the basic properties such as pressure, fugacity, and enthalpy, the equation can be extrapolated up to the limits of the chemical stability of carbon dioxide. Independent equations for the vapor pressure and for the pressure on the sublimation and melting curve, for the saturated liquid and vapor densities, and for the isobaric ideal gas heat capacity are also included. Property tables calculated from the equation of state are given in the appendix. © 1996 American Institute of Physics and American Chemical Society. |
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JANAF thermochemical tables, 1978 supplement J. Phys. Chem. Ref. Data 7, 793 (1978); http://dx.doi.org/10.1063/1.555580 (148 pages)
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The thermodynamic tabulations previously published in NSRDS–NBS 37, the 1974 Supplement (J. Phys. Chem. Ref. Data 3, 311 (1974), and the 1975 Supplement (J. Phys. Chem. Ref. Data 4, 1 (1975) are extended by 131 new and revised tables. The JANAF Thermochemical Tables cover the thermodynamic properties over a wide temperature range with single phase tables for the crystal, liquid, and ideal gas state. The properties given are heat capacity, entropy, Gibbs energy function, enthalpy, enthalpy of formation, Gibbls energy of formation, and the logarithm of the equilibrium constant for formation of each compound from the elements in their standard reference states. Each tabulation lists all pertinent input data and contains a critical evaluation of the literature upon which these values are based. Literature references are given. |
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Electrical resistivity of copper, gold, palladium, and silver J. Phys. Chem. Ref. Data 8, 1147 (1979); http://dx.doi.org/10.1063/1.555614 (152 pages)
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In this work, recommended values for the electrical resistivity as a function of temperature from the cryogenic region to well beyond the melting point are given for bulk pure copper, gold, palladium, and silver. In addition to the total electrical resistivity values for the solid state, intrinsic electrical resistivity values are presented from cryogenic temperatures to the melting point. The values are corrected for the change in geometry due to thermal expansion. The recommendations are based on theoretical considerations and on the experimental data found in the open literature. That available experimental data together with information pertaining to the specimen characterization and measurement conditions are included in this work. The methods of data evaluation and other considerations used in arriving at the recommendations are described. For the solid state, an interpolation scheme is given to aid in the determination of values between those supplied in the tables; for the liquid state, equations are given. |
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Atomic radiative and radiationless yields for K and L shells J. Phys. Chem. Ref. Data 8, 307 (1979); http://dx.doi.org/10.1063/1.555594 (21 pages)
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The available body of information on (a) fluorescence, Auger, and Coster‐Kronig yields, (b) radiative and radiationless transition rates, (c) level widths, (d) x‐ray and Auger line widths, (e) x‐ray and Auger spectra, and (f) Coster‐Kronig energies has been used to generate an internally consistent set of values of atomic radiative and radiationless yields for the K shell (5 ?Z?110) and the L subshells (12 ?Z?110). Values of fluorescence yields ωk, ω1, ω2, ω3, Coster‐Kronig yields F1, F1.2, F1.3, F1.3, F2.3. Auger yields ak, a1, a2, a3, and effective fluorescence yields ν1 and ν2 are presented in tables and graphs. Estimates of uncertainties are given. Updated and expanded graphs of partial and total widths of K, L1, L2, and L3 levels are presented as well as a reference list of papers published since about 1972. |
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Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related Compounds J. Phys. Chem. Ref. Data 15, 1087 (1986); http://dx.doi.org/10.1063/1.555759 (193 pages)
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This document contains evaluated data on the kinetics and thermodynamic properties of species that are of importance in methane pyrolysis and combustion. Specifically, the substances considered include H, H2, O, O2, OH, HO2, H2O2, H2O, CH4, C2H6, HCHO, CO2, CO, HCO, CH3, C2H5, C2H4, C2H3, C2H2, C2H, CH3CO, CH3O2, CH3O, singlet CH2, and triplet CH2. All possible reactions are considered. In arriving at recommended values, first preference is given to experimental measurements. Where data do not exist, a best possible estimate is given. In making extrapolations, extensive use is made RRKM calculations for the pressure dependence of unimolecular processes and the BEBO method for hydrogen transfer reactions. In the total absence of data, recourse is made to the principle of detailed balancing, thermokinetic estimates, or comparisons with analogous reactions. The temperature range covered is 300–2500 K and the density range 1×1016–1×1021 molecules/cm3. This data base forms a subset of the chemical kinetic data base for all combustion chemistry processes. Additions and revisions will be issued periodically. |
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J. Phys. Chem. Ref. Data 22, 113 (1993); http://dx.doi.org/10.1063/1.555934 (150 pages)
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Quenching of excited singlet and triplet states of many substances by ground state molecular oxygen produces singlet oxygen, the lowest electronically excited singlet state of molecular oxygen, O2(1Δg). The fractions of singlet and triplet states quenched which produce singlet oxygen and the quantum yields of formation of singlet oxgyen in fluid solutions have been critically compiled. Methods for determination yield parameters have been reviewed. Data have been compiled from the literature through 1991. Photosensitizers such as aromatic hydrocarbons, aromatic ketones and thiones, quinones, coumarins, fluoresceins, transition metal complexes, and heterocyclics are included in Table 1. Porphyrins and phthalocyanines are included in Table 2. Other materials which have been investigated for singlet oxygen production, such as dyes and drugs, are collected in Table 3 along with heterogeneous systems such as polymer‐bound photosensitizers. |
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Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update J. Phys. Chem. Ref. Data 27, 413 (1998); http://dx.doi.org/10.1063/1.556018 (244 pages)
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The available data on gas-phase basicities and proton affinities of approximately 1700 molecular, radical and atomic neutral species are evaluated and compiled. Tables of the data are sorted (1) according to empirical formula and (2) according to evaluated gas basicity. This publication constitutes an update of a similar evaluation published in 1984. © 1998 American Institute of Physics and American Chemical Society. |
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