Volume 33, Issue 4, December 2004
Index of content:
Vapor Pressures, Critical Parameters, Boiling Points, and Triple Points of Ammonia and Trideuteroammonia33(2004); http://dx.doi.org/10.1063/1.1691451View Description Hide Description
A simple extended corresponding-states principle is used to represent the vapor pressure of ammonia and trideuteroammonia from the triple point to critical point and to describe the available experimental data along with extrapolation beyond their ranges of available experimental data. This work takes advantage of the adoption of the ITS-90 temperature scale and of the new critical parameters obtained from the extended corresponding-states principle. The vapor pressure data are described within their scatter in the entire temperature range. Comparisons with the available data show that the extended corresponding-states principle may calculate the vapor-pressure values within 0.05%–0.1% The substance-dependent characteristic parameters are given, such as critical temperature, critical density, critical pressure, acentric factor, and aspherical factor. The values of the pressures, along with their first and second derivatives as a function of temperature over the entire region from the triple point to the critical point are tabulated and recommended for scientific and practical uses.
33(2004); http://dx.doi.org/10.1063/1.1707042View Description Hide Description
Previous studies on the even parity autoionizing levels of calcium have been critically evaluated. These levels have been studied within the framework of the weakest bound electron potential model theory. 30 series are treated and the results are listed here. In these calculations, the coupling scheme is used. It is remarkable that the perturbation approach that has been emphasized in our calculations so as to adequately consider the correlation between the two excited electrons is more important than in the case of singly excited states. Compared with the experimental results and the values from other theoretical methods, the present results are in concurrence with the experimental data, and showed comparative accuracy with other methods. Some levels, which have not been reported previously, are predicted here.
Total, Partial, and Differential Ionization Cross Sections in Proton–Hydrogen Atom Collisions in the Energy Region of 0.1–10 keV/u33(2004); http://dx.doi.org/10.1063/1.1710897View Description Hide Description
Single-differential, partial, and total ionization cross sections for the proton–hydrogen atom collision system in the energy region of 0.1–10 keV/u are determined by using the molecular-orbital close-coupling method within a semiclassical formalism. The present cross sections are in an excellent agreement with the recent experiments of Shah et al. [J. Phys. B. 31, L757 (1998)], but decrease more rapidly than the cross sections measured by Pieksma et al. [Phys. Rev. Lett. 73, 46 (1994)] with decreasing energy. The numerical data for all calculated cross sections are included in this paper. A critical evaluation of the existing data for the ionization process in the keV energy range is performed both for the experiment and theory. The recommended data are obtained from a converged close-coupling expansion, which in total includes 362 bound and continuum channels with their wave functions augmented by the electron translation factor in order to insure the correct scatteringboundary condition.
33(2004); http://dx.doi.org/10.1063/1.1796671View Description Hide Description
E1, M1, E2, M2, E3, and M3 transition probabilities for hydrogen-like atoms are calculated with point-nucleus Dirac eigenfunctions for and up to large quantum numbers and increasing existing data more than a thousandfold. A critical evaluation of the accuracy shows a higher reliability with respect to previous works. Tables for hydrogen containing a subset of the results are given explicitly, listing the states involved in each transition, wavelength, term energies, statistical weights, transition probabilities, oscillator strengths, and line strengths. The complete results, including 1 863 574 distinct transition probabilities, lifetimes, and branching fractions are available at http://www.fisica.unam.mx/research/tables/spectra/1el
Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature Using Group Additivity: An Amendment33(2004); http://dx.doi.org/10.1063/1.1797811View Description Hide Description
An amendment to a second-order group additivity method for the estimation of the heat capacity of pure organic liquids as a function of temperature in the range from the melting temperature to the normal boiling temperature is reported. The temperature dependence of various group contributions and structural corrections is represented by a series of second order polynomial expressions. The group contribution parameters have been developed from an extended database of more than 1800 recommended heat capacity values. The present method should be more versatile and more accurate than the previous one [Růžička and Domalski, J. Phys. Chem. Ref. Data 22, 597, 619 (1993)] due to the use of a larger database and an improved procedure for parameter calculation.
A Unique Equation to Estimate Flash Points of Selected Pure Liquids Application to the Correction of Probably Erroneous Flash Point Values33(2004); http://dx.doi.org/10.1063/1.1835321View Description Hide Description
A simple empirical equation is presented for the estimation of closed-cup flash points for pure organic liquids. Data needed for the estimation of a flash point (FP) are the normal boiling point the standard enthalpy of vaporization at 298.15 K of the compound, and the number of carbon atoms in the molecule. The bounds for this equation are: Compared to other methods (empirical equations, structural group contribution methods, and neural network quantitative structure–property relationships), this simple equation is shown to predict accurately the flash points for a variety of compounds, whatever their chemical groups (monofunctional compounds and polyfunctional compounds) and whatever their structure (linear, branched, cyclic). The same equation is shown to be valid for hydrocarbons, organic nitrogen compounds, organic oxygen compounds, organic sulfur compounds, organic halogen compounds, and organic silicone compounds. It seems that the flash points of organic deuterium compounds, organic tincompounds, organic nickelcompounds, organic phosphorus compounds, organic boron compounds, and organic germanium compounds can also be predicted accurately by this equation. A mean absolute deviation of about a standard deviation of about and a maximum absolute deviation of are obtained when predictions are compared to experimental data for more than 600 compounds. For all these compounds, the absolute deviation is equal or lower than the reproductibility expected at a 95% confidence level for closed-cup flash point measurement. This estimation technique has its limitations concerning the polyhalogenated compounds for which the equation should be used with caution. The mean absolute deviation and maximum absolute deviation observed and the fact that the equation provides unbiaised predictions lead to the conclusion that several flash points have been reported erroneously, whatever the reason, in one or several reference compilations. In the following lists, the currently accepted flash points for bold compounds err, or probably err, on the hazardous side by at least and for the nonbolded compounds, the currently accepted flash points err, or probably err, on the nonhazardous side by at least bicyclohexyl, sec-butylamine, tert-butylamine, 2-cyclohexen-1-one, ethanethiol, 1,3-cyclohexadiene, 1,4-pentadiene, methyl formate, acetonitrile, cinnamaldehyde, 1-pentanol, diethylene glycol, diethyl fumarate, diethyl phthalate, trimethylamine, dimethylamine, 1,6-hexanediol, propylamine, methanethiol, ethylamine, bromoethane, 1-bromopropane, tert-butylbenzene, 1-chloro-2-methylpropane, diacetone alcohol, diethanolamine, 2-ethylbutanal, and formic acid. For some other compounds, no other data than the currently accepted flash points are available. Therefore, it cannot be assessed that these flash point data are erroneous but it can be stated that they are probably erroneous. At least, they need experimental re-examination. They are probably erroneous by at least 1,3-cyclopentadiene, di-tert-butyl sulfide, dimethyl ether, dipropyl ether, 4-heptanone, bis(2-chloroethyl)ether, 1-decanol, 1-phenyl-1-butanone, furan, ethylcyclopentane, 1-heptanethiol, 2,5-hexanediol, 3-hexanone, hexanoic acid methyl ester, 4-methyl-1,3-pentadiene, propanoyl chloride, tetramethylsilane, thiacyclopentane, 1-chloro-2-methyl-1-propene, trans-1,3-pentadiene, 2,3-dimethylheptane, triethylenetetramine, methylal, N-ethylisopropylamine, 3-methyl-2-pentene, and 2,3-dimethyl-1-butene.
33(2004); http://dx.doi.org/10.1063/1.1797771View Description Hide Description
We have prepared a comprehensive critically evaluated compilation of the most accurate wavelength measurements for classified lines of neutral neon (Ne I) in its natural isotopic abundance. Data from 19 sources spanning the region 256 Å to 54 931 Å are included. Based on this line list we have derived optimized values for the energy levels of neutral neon. Tabular data for 1595 classified lines and 374 energy levels are provided. In addition to the observed wavelengths, we present revised wavelengths calculated from the optimized energy levels for all lines that have been previously recommended for use as secondary wavelength standards.
33(2004); http://dx.doi.org/10.1063/1.1797038View Description Hide Description
The recommended liquid–liquid equilibrium (LLE) data for 21 binary alkylbenzene–water systems have been obtained after critical evaluation of all data (392 data sets) reported in the open literature up to the middle of 2003. An equation for prediction of the alkylbenzene solubilities was developed. The predicted alkylbenzene solubilities were used for calculation of water solubility in the second liquid phase. The LLE calculations were done with the equation of state appended with a chemical term proposed by Góral. The recommended data were presented in the form of individual pages containing tables, all the references, and optionally figures.