Conceptual definition, 195 Condensed phases, 27, 68, 78 electrical properties, 78 Conductivity, electrical in metals, 8l in water solutions, 78 of solids, 80 [Pg.457]

Ionization in the condensed phase presents a challenge due to the lack of a precise operational definition. Only in very few cases, such as the liquefied rare gases (LRG), where saturation ionization current can be obtained at relatively low fields, can a gas-phase definition be applied and a W value obtained (Takahashi et al., 1974 Thomas and Imel, 1987 Aprile et al., 1993). [Pg.109]

With this definition, T is the numerical value of the activity for the substance under some pressure p. It is also the ratio of the fugacity of the pure condensed phase under pressure p to that of the phase under 1 bar pressure. [Pg.285]

Let us introduce a system of coordinates in which the flame is at rest. For the sake of definiteness we shall make the coordinate plane YOZ coincident with the interface between the condensed phase (briefly, c-phase) and the gas, with the c-phase located to the left at x < 0. In a system in which the flame is at rest, the material must move. The velocity of the material u [Pg.335]

The total interaction between two slabs of infinite extent and depth can be obtained by a summation over all atom-atom interactions if pairwise additivity of forces can be assumed. While definitely not exact for a condensed phase, this conventional approach is quite useful for many purposes [1,3]. This summation, expressed as an integral, has been done by de Boer [8] using the simple dispersion formula, Eq. VI-15, and following the nomenclature in Eq. VI-19 [Pg.232]

In the gaseous phase, an electron ejected from a molecule becomes free, and so for each filled electron level we have only one ionization potential. However, in the condensed phase an ejected electron can be in three different states free, quasi-free, and solvated. So the definition of the ionization potential becomes ambiguous. [Pg.310]

The term ionization may refer to different processes depending on the context. For radiation effects in the gas phase, it usually implies the removal of the least bound electron to infinity. Such a theoretical definition is not feasible in the condensed phase and it is necessary use a heuristic or operational procedure. Thus, in liquid hydrocarbons, one may use the electron scavenging reaction or a conductivity current to quantify the electrons liberated from molecules. It has only been possible to extrapolate the conductivity current at a low irradiation dose and at a relatively low external field to saturation in the cases of liquefied [Pg.80]

We define the cohesive energy Ecoh (Johansson, Skriver ) as the difference between the energy of an assembly of free atoms in their ground state (see Table 1 of Chap. A) and the energy of the same assembly in the condensed phase (the solid at 0 °K), (this definition yields a positive number for Ecoii). It coincides with the enthalpy of sublimation AHj (see Chap. A) (which is usually extrapolated at room temperature). [Pg.97]

Quinone oximes and nitrosoarenols are related as tautomers, i.e. by the transfer of a proton from an oxygen at one end of the molecule to that at the other (equation 37). While both members of a given pair of so-related isomers can be discussed separately (see, e.g., our earlier reviews on nitroso compounds and phenols ) there are no calorimetric measurements on the two forms separately and so discussions have admittedly been inclusive—or very often sometimes, evasive—as to the proper description of these compounds. Indeed, while quantitative discussions of tautomer stabilities have been conducted for condensed phase and gaseous acetylacetone and ethyl acetoacetate, there are no definitive studies for any pair of quinone oximes and nitrosoarenols. In any case. Table 4 summarizes the enthalpy of formation data for these pairs of species. [Pg.71]

Abstract The theoretical basis for the quantum time evolution of path integral centroid variables is described, as weU as the motivation for using these variables to study condensed phase quantum dynamics. The equihbrium centroid distribution is shown to be a well-defined distribution function in the canonical ensemble. A quantum mechanical quasi-density operator (QDO) can then be associated with each value of the distribution so that, upon the application of rigorous quantum mechanics, it can be used to provide an exact definition of both static and dynamical centroid variables. Various properties of the dynamical centroid variables can thus be defined and explored. Importantly, this perspective shows that the centroid constraint on the imaginary time paths introduces a non-stationarity in the equihbrium ensemble. This, in turn, can be proven to yield information on the correlations of spontaneous dynamical fluctuations. This exact formalism also leads to a derivation of Centroid Molecular Dynamics, as well as the basis for systematic improvements of that theory. [Pg.47]

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