Measurements of the Surface Elasticity in Medium Frequency Range Using the Oscillating Bubble Method

A study of kinetic molecular exchange processes in the medium frequency range by surface SHG on an oscillating bubble

“…Several models that describe the dynamic behavior of fluid surfaces are established. But experiments in the medium frequency range, e.g., with the oscillating bubble method, exhibit discrepancies to the theoretical models [8][9][10][11]. The reason is probably the assumptions about the structure of the adsorption layer under dynamic conditions.…”

“…However, near the CMC or the solubility limit the calculated parameters become unrealistically great, regardless of the approximation model and at least in this range the difference between ε m (c s ) and ε g (c s ), respectively ω m (c s ) and ω g (c s ), must be considered as verified. The comparison of experimental and calculated parameters was discussed in our previous articles in detail [9,11]. It leads to the conclusion that for the explanation of the results in critical concentration ranges additional, independent experiments are required.…”

“…(4) can be very well fitted to these experimental results, but, in the low concentration range, the experimental Gibbs elasticity, ε m (c s ), is larger than ε g (c s ) whereas for higher concentration near the CMC or the solution limit, ε m (c s ) and ω m (c s ) have too small values. These effects are very often verified by surface rheological measurements with the oscillating bubble method [9,11]. The method allows the determination of the modulus up to a magnitude of 150 mN/m in the frequency range 1 f 500 Hz.…”

“…It is introduced for formal reasons to characterize the influence of dissipative losses within the surface layer on the surface tension. Experimental results request this term [8][9][10][11][12][13][14]. Here we consider only the compositional effects because the solution used shows no influence of an intrinsic surface dilatational viscosity (κ = 0).…”

“…The surface dilatational modulus ε(f, c) was determined with the oscillating bubble method [4,8,9]. Within a closed chamber a small hemispherical bubble is produced at the tip of a capillary.…”