Solid surface energy definition

Consider now that some adsorption of liquid vapours on the solid surface occurs (Figure 1,34.b), leading to a reduction of its surface energy by a quantity Aliquid surface). For the sake of clarity, we denote by cr< v and W the solid surface energy and the work of adhesion in the absence of adsorption, while pure solid/pure liquid/vapour system held at constant temperature, the solid surface is in equilibrium with a saturated vapour of the liquid at a partial pressure of Psat, the equilibrium values of [Pg.45]

Good-Girifalco interaction parameter D E PACKHAM Definition of (p evaluation for dispersion force interface interfacial tension solid surface energies... 

If, when a liquid drop is placed on a smooth surface, the forces of adhesion between the solid and the liquid are greater than the forces of cohesion of the liquid, then the liquid will spread and will perfectly wet the surface spontaneously. If the forces reach an intermediate balance determined by the interfacial energies ylv, ysj and ysv, then the liquid drop will form a definite contact angle (0) with the solid surface (Figure 4.12). 

This review deals with the applications of photolurainescence techniques to the study of solid surfaces in relation to their properties in adsorption, catalysis, and photocatalysis, After a short introduction, the review presents the basic principles of photolumines-cence spectrosajpy in relation to the definitions of fluorescence and phosphorescence. Next, we discuss the practical aspects of static and dynamic photoluminescence with emphasis on the spectral parameters used to identify the photoluminescent sites. In Section IV, which is the core of the review, we discuss the identification of the surface sites and the following coordination chemistry of ions at the surface of alkaline-earth and zirconium oxides, energy and electron transfer processes, photoluminesccncc and local structure of grafted vanadium oxide, and photoluniinescence of various oxide-... 

Only a few definitions will be recalled in this instance. The surface energy of a solid (7s... 

Figure 4-4 (a) Geometry of a pencil of light in solid angle dw traversing a unit of surface dSh 6 is the inclination of the beam relative to the surface, (b) Definition of the azimuthal () and zenith (0) angles, (c) Balance of energy fluxes for a thin layer between altitude z and z + 5z. 

There remains the question of the physical-i.e., operational [9] -definition of the terms. It appears to the writers that the derivation as a force balance is merely intuitional, and, as a consequence, it leaves the quantities and yg o undefined operationally. Thus, if these be viewed as forces parallel to the solid surface, one must ask with what property of the solid they are to be identified. Unlike the case with liquids, there is for solids a surface or stretching tension (the work per unit stretching of the surface [20, 25, 28]), in general nonisotropic. If this is what is involved, liquid drops on a crystalline surface of low symmetry should not be circular in cross section this is apparently contrary to observation. From the thermodynamic derivation, however, we see that one is dealing with the work of exchanging one type of solid interface for another, and that surface free energies, not stretching tensions, are the proper quantities. 

Knudsen s definition is valid for an exchange of energy at a solid surface... 

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