Organic liquid-air interfaces

Jarvis, N.L. and Zisman, W.A. "Surface Activity of Fluorinated Organic Compounds at Organic-Liquid/Air Interfaces Part II. Surface Tension vs Concentration Curves, Adsorption Isotherms, and Force-Area Isotherms for Partially Fluorinated Carboxylic Esters," Naval Research Labs Report 5364, Surface Chemistry Branch, Chemistry Division, October 8, 1959. 

Of especial interest is that the same approach in defining wetting agents in aqueous solutions can also apply to nonaqueous solutions. Increasing interest has been shown in the behavior of surface-active agents at organic liquid-air interfaces. Many of the earliest such studies were made on compounds previously found effective as surface-... 

A series of studies of surface activity of soluble and insoluble compounds at organic liquid-air interfaces has been reported by Zis-man, Ellison, Bernett, and Jarvis [4,10,11,16,17,18]. The most surface active compounds were foxmd to be various fluorocarbon derivatives having the proper organophobic-organophilic balance. If one considers a plastic solid to be either a supercooled liquid or a liquid of very high viscosity, one would e3q)ect many of these partially fluorinated compoimds also to manifest great surface activity when dissolved in... 

Second harmonic generation has been recognized as a powerful probe to study the electronic states at surfaces and interfaces [16]. Under the electric dipole approximation, second-order nonlinear processes are forbidden in centrosymmetric systems. This principle makes the phenomena surface-specific in many cases. Indeed, the capability of SHG spectroscopy to explore surface electronic states has been demonstrated on various systems, dye molecules at solid/liquid interfaces [17], organic molecules at liquid/air interfaces [18], semiconductor surface states [19], organic molecules at metal surfaces [20], and so on. 

In Langmuir-Blodgett deposition (Fig. 10.24e), a film of molecules (with amphiphilic properties) is forced in a densely packed layer at a liquid-air interface or at a liquid-liquid (lipophilic/hydrophilic) interface. The substrate (submerged into the liquid beforehand) is pulled from the liquid to air to adsorb a monolayer. With this technique, the monolayer is forced into an organization by narrowing the organization area with movable sidewalls. The technique has been particular successful on molecules with liquid crystal properties [133, 87],... 

Langmuir monolayers are liquid-air interfaces (typically water/air) which are decorated with adsorbed amphiphiles (Fig. 4) which self-organize at the surface with their polar heads in the water and the aliphatic tails extending above the surface. The dipoles are more or less perpendicular to the surface and, in this case, their mutual interaction is repulsive. It has been suggested that the dipolar interaction plays a central role in the organization of the amphiphiles at the interface. 

In the current chapter, the principles of Raman excitation and interface-selective detection of vibrational coherence are described, including applications to air/liquid, liquid/liquid, air/solid interfaces, and an organic submonolayer. 

Sow spreading coefficient of organic liquid at air-water table interface (dyn/cm)... 

Obviously, the transfer between the pure organic liquid and the air must be air-phase controlled. Since the MCF concentrations at the interface are expressed in terms of the concentrations in the air, apply Eq. 20-9a, where the pure MCF takes over the role of the water ... 

Stability of both foam and asymmetric aqueous films at the surface of organic liquids of different polarity has been studied as function of the surfactant concentration [551], Microscopic foam films were obtained in a glass cuvette (Tig. 3.120,c) by blowing an air bubble at the tip of a vertical capillary immersed into the surfactant solution. With a micrometric screw (not shown in the figure) the bubble was pressed carefully onto the solution/air interface, thus forming the film. 

Many theories have been advanced concerning the mechanisms involved in surfacing the mineral particles so as to create a hydrophobic hydrocarbon film on the mineral surface, and many investigations have been carried out to define these mechanisms. When firoth flotation is used in an aqueous medium that carries the solids to be separated (together with dispersed air bubbles and possibly an organic liquid) a three- or possibly a four-phase system must be considered. In most froth flotation processes, the solid particles are initially completely water-wetted, and the solid-liquid interface must be replaced by... 

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