Pockels trough

Pockels trough - Pockels Poggendorff, Johann Christian... 

Figure 1.5.10 Schematic drawing of a Pockels trough used to form compact molecular monolayers on a water surface. The deposition takes place on the downward stroke if hydrophobic interaction is responsible for deposition (hydrophobic surface) and on the upward stroke if hydrophihc surface-monolayer interactions are more important. If the deposition area is equal to the loss of the monolayer on the air/water interface (deposition ratio equal to 1), it is assumed that perfect deposition has taken place. If the ratio is near unity in both upward and downward strokes, the material is deposited in the Y mode, which is the most stable multilayer structure (b). If the deposition ratio is near unity in the down stroke and zero on the up stroke, the deposition is in the X mode (a). The surface is hydrophobic and am-phiphiles are bound in the A orientation. The converse situation leads to Z-mode multilayers (c B orientation). X- and Z-types often rearrange to Y-type multilayers.

Fig. ni-14. Cross section of the PLAWM (Pockels-Langmuir-Adam-Wilson-McBain) trough. 

Pockels described in the letter her design of a rectangular tin trough with a thin tin strip laid across it. The trough was filled to the brim with water, with a thin layer of oil covering the surface of the water on one side of the tin strip and clean water on the other side. The tin strip served to vary the area of the oil-contaminated surface, and a balance measured the force necessary to lift a small disk (a button) from the surface. Pockels used this setup to study the surface tension of the oil-contaminated layer. 

The first to perform wave-damping measurements in a kind of Langmuir trough, i.e., under different compression status of the monolayer, was Agnes Pockels (1891). Ironically, she described for the first time an apparatus that was... 

Figure 5.3 Film balances a. Langmuir trough having a movable barrier and a Wilhelmy tensiometer to measure the spreading pressure, n, for water insoluble monolayers, b. PLAWM (Pockels, Langmuir, Adam, Wilson and McBain) trough used for partially water-soluble monolayers, where a flexible membrane, which is fixed to the barrier, separates the surfactant solution and pure water departments to prevent the passage of dissolved surfactant molecules into the pure water department beneath the barrier.

Film Balance A shallow trough that is filled with a liquid on top of which is placed material that may form a monolayer. The surface area available can be adjusted by movable barriers, and any surface pressure thus created can be measured by means of a float. Also called Langmuir Film Balance, Langmuir Trough, and Pockels—Langmuir—Adam—Wilson—McBain Trough or PLAWM Trough. 

PLAWM Trough (Pockels—Langmuir—Adam—Wilson—McBain Trough)... 

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