Oscillating Bubble Tensiometry: A Method for Measuring the Surfactant Adsorptive-Desorptive Kinetics and the Surface Dilatational Viscosity

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

“…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).…”

“…Then Eq. (8), respectively (12), describes only the molecular exchange at the plane x = −d. In the level range of the modulus this exchange is negligible, which is however not the case for the exchange between monolayer and sublayer.…”

“…It leads in the high frequency range, defined by a limit frequency f g (c s ), to Eq. (12). Therefore, the relative change in the effective surface concentration Γ is given by this equation if the surface dilatational modulus reaches a constant level ε(f, c s ) = ε m (c s ) = const.…”

Bubble Oscillations in a Closed Cell

“…Taking the viscous term into consideration one obtains a small correction to Eqs. [8] and [9] reflecting the damping of acoustical waves. As we consider in this study distances smaller than the wavelength where the damping is known to be small, we can neglect the damping terms in the equations for the cell (but not for the capillary, where the viscous resistance is large due to the very small capillary radius).…”

“…Very often the cell with solution is opened and the compartment containing the gas phase is closed as shown in Fig. 1 (7)(8)(9). The meniscus oscillations are imposed by changing the compartment volume.…”