Volume 34, Issue 1, March 2005
Index of content:
34(2005); http://dx.doi.org/10.1063/1.1799251View Description Hide Description
Cross section data have been compiled from the literature (to the end of 2003) for electron collisions with water molecules. All major collision processes are reviewed including: total scattering, elastic scattering, momentum transfer, excitation of rotational, vibrational, and electronic states, ionization, electron attachment, dissociation, and emission of radiation. In each case we assess the collected data and provide a recommendation of the values of the cross section to be used. They are presented in a tabular form. Isotope effects versus are discussed as far as information is available.
34(2005); http://dx.doi.org/10.1063/1.1797791View Description Hide Description
An extensive study of the available spectroscopicinformation on four gallium monohalides has been conducted. The literature survey extends to early 2003 and the experimental and theoretical data on the molecular constants for the ground state, as well as for the excited states of these molecules, is presented. A brief discussion on the spectroscopicproperties of different electronic states, ionization potentials,ground statedissociation energies, and percentage ionic character are given. The Rydberg–Klein–Rees potentials for the electronic states and centrifugal distortion constants for the observed vibrational levels for the electronic states of GaX Cl, Br, and I) are also presented.
Intrinsic Wavelength Standard Absorption Bands in Holmium Oxide Solution for UV/visible Molecular Absorption Spectrophotometry34(2005); http://dx.doi.org/10.1063/1.1835331View Description Hide Description
The transmittance minima of 18 absorption bands of a solution of 40 g/L holmium oxide in 10% (volume fraction) perchloric acid are certified as intrinsic traceable wavelength standards, by means of a multicenter measurement on material from a single source coupled with comparisons of a variety of preparations of the material evaluated on a single instrument. Fit-for-purpose artifact standards for the experimental calibration or validation of wavelength scales of chemical spectrophotometers can be carefully produced by end users themselves or by commercial standards producers. The intrinsic (data) standard confers traceability to the SI unit of length in place of costly transfer artifacts and repetitive calibration procedures. Certified values are provided for instrumental spectral bandwidths of 0.1–3.0 nm in 0.1 nm intervals, and information values are provided to a spectral bandwidth of 10 nm at wider intervals. Expanded uncertainties are typically less than for certified band positions.
34(2005); http://dx.doi.org/10.1063/1.1836764View Description Hide Description
The Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry completed its last review of the isotopic compositions of the elements as determined by isotope-ratio mass spectrometry in 2001. That review involved a critical evaluation of the published literature, element by element, and forms the basis of the table of the isotopic compositions of the elements (TICE) presented here. For each element, TICE includes evaluated data from the “best measurement” of the isotopeabundances in a single sample, along with a set of representative isotopeabundances and uncertainties that accommodate known variations in normal terrestrial materials. The representative isotopeabundances and uncertainties generally are consistent with the standard atomic weight of the element and its uncertainty recommended by CAWIA in 2001.
A New Functional Form and New Fitting Techniques for Equations of State with Application to Pentafluoroethane (HFC-125)34(2005); http://dx.doi.org/10.1063/1.1797813View Description Hide Description
A widely used form of an equation of state explicit in Helmholtz energy has been modified with new terms to eliminate certain undesirable characteristics in the two phase region. Modern multiparameter equations of state exhibit behavior in the two phase that is inconsistent with the physical behavior of fluids. The new functional form overcomes this dilemma and results in equations of state for pure fluids that are more fundamentally consistent. With the addition of certain nonlinear fitting constraints, the new equation now achieves proper phase stability, i.e., only one solution exists for phase equilibrium at a given state. New fitting techniques have been implemented to ensure proper extrapolation of the equation at low temperatures, in the vapor phase at low densities, and at very high temperatures and pressures. A formulation is presented for the thermodynamic properties of refrigerant 125 (pentafluoroethane, using the new terms and fitting techniques. The equation of state is valid for temperatures from the triple point temperature (172.52 K) to 500 K and for pressures up to 60 MPa. The formulation can be used for the calculation of all thermodynamic properties, including density, heat capacity,speed of sound, energy, and saturation properties. Comparisons to available experimental data are given that establish the accuracy of calculated properties. The estimated uncertainties of properties calculated using the new equation are 0.1% in density, 0.5% in heat capacities, 0.05% in the vapor phase speed of sound at pressures less than 1 MPa, 0.5% in the speed of sound elsewhere, and 0.1% in vapor pressure. Deviations in the critical region are higher for all properties except vapor pressure.
34(2005); http://dx.doi.org/10.1063/1.1797812View Description Hide Description
Absolute rate constants for reactions of phenoxyl radicals in solution have been compiled and evaluated from the literature (172 citations). Rate constants are included for phenoxyl radicals bearing various substituents, including semiquinone radicals and radical ions, as well as aroxyl radicals derived from polycyclic aromatic compounds. The reactions tabulated include self-reactions of the radicals, reactions with other radicals, reactions with inorganic compounds, and reactions with organic compounds. A subset of the latter group includes electron transferreactions for which the rate constants of both the forward and the reverse reaction have been measured. The radicals were generated by radiolysis, photolysis, thermolysis, or chemical reactions, and their rate constants were determined generally by kinetic spectrophotometry or electron spin resonance.
IUPAC-NIST Solubility Data Series. 80. Gaseous Fluorides of Boron, Nitrogen, Sulfur, Carbon, and Silicon and Solid Xenon Fluorides in all Solvents34(2005); http://dx.doi.org/10.1063/1.1794762View Description Hide Description
The literature has been searched through 2002 June for solubility data on the gases 1,1,1,2- 1,1,1- 1,1- 1,1- and and the solids and in all solvents. The data are compiled here. Where feasible evaluations have been carried out. The evaluations were mostly carried out for water as a solvent as the water systems are the most extensively studied. For other systems there is often only one set of measurement or two sets of measurements, which do not agree well. Evaluation of such systems will have to wait on more experimental measurements.