Liquid Surface Energy Research Articles

Relation between bulk compressibility and surface energy of electron-hole liquids

Attention is drawn to the existence of an empirical relation χσ/ a B ∗ ∼ 1 between the compressibility, the surface energy and the excitonic radius in electron-hole liquids.

On the predictions of total surface energy of pure liquids

In conclusion it may be stated that the semiempirical expression Eq. [4], in which the shape of molecules in the liquid surface is approximated by a sphere, can be used for semiquantitative predictions of total surface energies of various classes of liquids. It is also valid if the temperature of the liquid varies in the limits approximately between 0 and 40°C. Absolute error of the calculated values is mostly within 10% of absolute values. It cannot be applied, however, to the first two carboxylic acids and monohydric alcohols, as well as to higher paraffins with the number of C-atoms >10, because the calculated values are too low in comparison with the experimental ones. Equation [4] is based on a simple molecular model; it, however, contains exclusive macroscopic parameters of the liquid, which adds much, together with the simple form of Eq. [4], to its applicability. Although derived originally for nonpolar liquids, its validity extends to a larger variety of molecular types than expected. The explanation of this fact lies, first of all, in the enhanced symmetry of the molecular holes at the surface of pure liquids, as compared with the bulk.

Surface energy of electron-hole liquid in germanium at zero and finite〈111〉 uniaxial stress

In the framework of density-functional formalism we show that in a calculation of surface energy of electron-hole liquid (EHL) in germanium the inclusion of first gradient correction to exchange-correlation energy has a significant quantitative effect. The surface energy of EHL in Ge under very large 〈111〉 stress is found to be a factor of sixteen smaller than the value in Ge at zero stress.

Determination of surface energy of solids and liquids by means of an ultrasonic method : Wawra, H.H. 14 (December 1972) 413

The energy loss of iodine in gold was investigated at energies below the Bragg peak. With the present work, the range of the available experimental data is extended to significantly lower energies, while the nuclear stopping power contribution is taken into account. Experiments were performed on thin film targets in reflection geometry. Electronic stopping cross sections were extracted by different approaches from experimental spectra. The obtained results have been compared to tabulated values from SRIM and previously published experimental data, where available. For all energies the obtained values are consistently higher than predicted by SRIM. Monte Carlo simulations (TRIM) have been performed to study path length distributions and the influence of nuclear stopping on the total energy loss. The results from the calculations indicate that the experimental geometry might be an important factor affecting the observed energy loss due to a selection of specific trajectories.

Glass and glaze

I read the article by Mr H Charnock ('The float glass process') in the April issue of Physics Bulletin with great interest, for I recently had occasion to think about the stability of glaze layers on pottery, in which the essential physics is the same. For a liquid layer on a solid the appropriate form of Langmuir's equation is easily derived, and it is convenient to substitute from the surface energy equilibrium relation so as to eliminate the unknown solid–liquid and solid surface energies in favour of the observable liquid surface energy γ and the contact angle θ.

Surface energy of liquids isolated in narrow capillaries

This paper presents a conceptual and mathematical model for the surface tension of liquids in narrow capillaries isolated from a reservoir. A pure liquid is viewed as a two component system consisting of vacancies as well as the molecules of the liquid. Desorption of vacancies takes place at the solid-liquid interface. The attendent increase in vacancy concentration at the liquid-vapor interface results in a greater average intermolecular distance and higher attractive forces. The equation relating the change in surface tension at the liquid-vapor interface is, dγ dA SL = (F SV − F SL ) A LV . This relation is used to derive the Fisher equation for the strength of liquid bridges between two spheres without the use of the reduced pressure device. This approach considers the properties of a liquid in small capillaries as part of a composite system and the results support the work of Shereshefsky and Derjaguin who have observed the abnormal behavior of liquids in small capillaries.

Application of wetting theory to the non-reactive liquid metal-graphite systems

An attempt has been made to correlate the published contact angle data for graphite-liquid metal systems with the theory of liquid-solid wetting phenomena. To establish the reasonableness of the approach, the potential expression for dispersion interaction was employed for mercury, and the magnitude of the contribution from dispersion forces to the liquid surface energy of mercury, γLd, was calculated to be 193 erg/cm2. This compares favourably with the published experimental value of 200 erg/cm2. Similarly the γLd values for liquid metals of known contact angle with graphite were calculated and subsequently substituted in a modified Young equation in order to calculate the respective values of Φ. The parameter, Φ, has been defined by Girifalco and Good as the ratio of adhesion and cohesion forces for any two phases in contact. The calculated values of Φ were observed to rise to a maximum for all metals in the same periodic group as carbon, which would be predicted for “chemically similar” phases.

Solvent‐induced crack growth in rubbery block polymers

AbstractThe rapid cracking of lightly stressed rubbery block polymers of styrene and isoprene in certain liquids and vapors has been examined experimentally, by using model test pieces containing a single crack. Solvents which preferentially dissolve the rigid molecular end blocks rather than the rubbery center blocks are efficient cracking agents. The stress required for crack growth to occur is shown to be in accord with a simple energy criterion: the stored elastic energy must be sufficient to provide a characteristic energy for the newly formed surface. This characteristic energy ranges from values close to the surface energy of simple liquids up to about 100 times this value for thicker test pieces or slowly diffusing vapors, when some tearing of an incompletely swollen core is inferred. “Induction times,” before the initial crack starts to grow, are shown to be due to a progressive increase in stored energy under a constant stress as the material absorbs solvent and softens until the critical energy criterion is met. Thus, a timedependent fracture process is shown to be in accord with a constant energy criterion. Above the critical condition the rate of crack growth depends strongly upon stress, like tearing of amorphous elastomers, and the crack then accelerates rapidly.

Application of the sessile drop method to the determination of the surface energy and density of liquids wetting the backing material

1. A procedure, based on the sessile drop method, is proposed for determining the free surface energy and density of melts wetting the material of solids in contact with the latter. 2. On the examples of ethyl alcohol and vacuum oil, which wet copper, the possibility is shown of forced generation of drops with the maximum diameter on copper backing plates having the shape of a solid of revolution with an acute angle between the horizontal and the side surface. A linear relationship is shown to exist between the maximum angle formed by the horizontal and the tangent at any point on the wetting perimeter, and the edge point angle of the backing plate. 3. The method proposed was applied to the high-temperature determination of the free surface energy of copper and calcium fluoride on molybdenum backing plates. 4. The sessile drop method in conjunction with the proposed procedure for determining the free surface energy and density of liquids wetting the backing material is universal.

Heat of Vaporization and Surface Energy of Several Liquids

Heat of Vaporization and Surface Energy of Several Liquids

Studies of the molecular forces involved in surface formation. I. The surface energies of pure liquids

The first page of this article is displayed as the abstract.

On the energy and entropy of liquid surfaces

On the energy and entropy of liquid surfaces

Calculation of the Surface Energies of Several Liquids

Calculation of the Surface Energies of Several Liquids

Surface Energy of Liquids

The paper contains: (1) A brief characterization of the intermolecular forces producing surface tension and similar phenomena. (2) A review of thermodynamic relations and the development of a statistical theory of surface energy resulting in Eq. (9). (3) The results of a calculation of the surface energies of seven liquids on the basis of this formula, and their comparison with experiment. The agreement is in all cases as good as is consistent with the uncertainty of the data from which the calculation starts, and may be taken to indicate the applicability of the present theory of molecular forces to simple problems connected with the liquid state.

LXVI. On a new application of the potential energy of liquid surfaces

LXVI. On a new application of the potential energy of liquid surfaces

Scientific Serials

Bulletin de l'Académic Roy ale de Belgique, No. 4.—Besides communications on the blood of the lobster (Fredericq), displacement of spectral lines of stars (Spee), and perpetual motion (Plateau), we have here a paper by M. Fredericq on the theory of respiratory innervation; he is led to regard the spinal cord as containing an inspiratory centre and an expiratory centre, chloral acting to paralyse the former.—M. van der Mensbrugghe contributes a paper on new applications of the potential energy of liquid surfaces, dealing with the principal cause of loss of charge by water-jets, origin of the energy of motion acquired by waves of the sea, cause of production lbf bars at the mouths of certain rivers, and origin of the force of the Gulf Stream.—M. De Selys Longcharnps communicates the additions to the synopsis of the Calopterygines.

V. On the application of thermodynamics to the study of the variations of potential energy of liquid surfaces

V. <i>On the application of thermodynamics to the study of the variations of potential energy of liquid surfaces</i>

LVI. On the application of thermodynamics to the study of the variations of potential energy of liquid surfaces. Divers consequences. (Preliminary communication.)

LVI. <i>On the application of thermodynamics to the study of the variations of potential energy of liquid surfaces. Divers consequences</i>. (<i>Preliminary communication</i>.)