Volume 28, Issue 1, January 1999
Index of content:
28(1999); http://dx.doi.org/10.1063/1.556034View Description Hide Description
The thermodynamic properties of the system were examined in order to provide: (1) an improved equation for the osmotic coefficient as a function of molality and temperature for purposes of isopiestic measurements, (2) a determination of the thermodynamic properties of the standard-state solution process, and (3) a test of the accuracy of the enthalpy of solution values for KCl(cr), a calorimetric standard. New equations that describe the thermodynamic properties of the system were obtained from previously published measurements for this system. The measured values included in the fitted equations spanned the range of temperature from approximately 260 to 420 K for KCl(aq) and 1.5 K to 1033.7 K for KCl(cr). New equations and/or values for the following properties are given in the present work: (1) thermal properties of KCl(cr) from 0 K to the melting point, 1045 K, (2) the change in chemical potential for both KCl and in KCl(aq) as a function of temperature, and molality, valid from 260 to 420 K, and (3) standard-state properties for the aqueous solution process. The effect of heat treatment on the determination of enthalpy of solution values was also examined. This examination indicated that the NIST recommendation of heating Standard Reference Material 1655, potassium chloride, at 800 K for a minimum of 4 h prior to its use in calorimetercalibration, should probably not be followed. The heat treatment recommended by the NIST certificate appears, at this point, to have a higher probability of corrupting the sample than improving the accuracy of the measurement.
28(1999); http://dx.doi.org/10.1063/1.556035View Description Hide Description
An analysis is given of the consistency of calculated and measured electron inelastic mean free paths (IMFPs) near solid surfaces for electron energies between 50 and the energy range of relevance for surfaceanalysis by Auger electron spectroscopy and x-ray photoelectron spectroscopy. This evaluation is based on IMFPs calculated from experimental optical data and on IMFPs measured by elastic-peak electron spectroscopy (EPES). We describe the methods used for the calculations and measurements, and we identify the various sources of uncertainty. Most of our evaluation is based on IMFPs for seven elemental solids (Al, Si, Ni,Cu,Ge, Ag, and Au) for which there were at least two sources of IMFP calculations and at least two sources of IMFP measurements for each solid. Our comparison of the calculated IMFPs showed a high degree of consistency for Al, Ni,Cu, Ag, and Au. The comparison of measured IMFPs showed greater scatter than for the calculated IMFPs, but reasonable consistency was found for the measured IMFPs of Cu and Ag. The measured IMFPs for four elements (Ni,Cu, Ag, and Au) showed good consistency with the corresponding calculated IMFPs. It is recommended that IMFPs for these four elements (determined from fits of a simple analytic expression to the calculated IMFPs for each element) be used as reference values in future EPES experiments. More limited comparisons have been made of calculated and measured IMFPs for four additional elements (Fe, Mo, W, and Pt) and of calculated IMFPs for six compounds ( KCl, poly(butene-1-sulfone), polyethylene, and polystyrene).
28(1999); http://dx.doi.org/10.1063/1.556033View Description Hide Description
The ideal gas thermodynamic properties of 27 organic nitro and nitrate organic compounds and two of their radicals are presented. Most of these compounds are high explosives (TNT, RDX, HMX, PETN, NPN, and NG), while others serve as propellants or specialty fuels (such as nitromethane). The thermodynamic properties were calculated using fundamental molecular data. The molecular data were gathered from the literature or calculated for this purpose. The enthalpy of formation of gaseous 1-nitropentane was estimated to be that of 1-nitrohexane to be for the ideal gas and for the liquid. All values refer to 298.15 K.
28(1999); http://dx.doi.org/10.1063/1.556036View Description Hide Description
Low-energy electron interactions with the molecule are reviewed. Information is synthesized and assessed on the cross sections for total electron scattering, total rotational excitation, total elastic electron scattering, momentum transfer, total vibrational excitation, electronic excitation, total dissociation into neutrals, total ionization, total electron attachment, and ion-pair formation. Similar data on the density-reduced ionization, density-reduced electron attachment, density-reduced effective ionization, electron transport coefficients, and electron attachment rate constant are also synthesized and critically evaluated. Cross sections are suggested for total electron scattering, total elastic electron scattering, total ionization,dissociation into neutrals, electron attachment, and ion-pair formation. A cross section is derived for the total vibrational excitation cross section via low-lying negative ion resonances. Data are suggested for the coefficients for electron attachment, ionization, and effective ionization, and for the rate constant for electron attachment. While progress has been made regarding our knowledge on electron–chlorine interactions at low energies there is still a need for: (i) improvement in the uncertainties of all suggested cross sections; (ii) measurement of the cross sections for momentum transfer, vibrational excitation, electronic excitation, and dissociativeionization; and (iii) accurate measurement of the electron transport coefficients in pure and in mixtures with rare gases. Also provided in this paper is pertinent information on the primary discharge byproducts Cl, and