Ellipsometric investigation of the skeletonization process of langmuir-blodgett films

Effect of the Skeletonization Process on Vapor Sorption into Langmuir−Blodgett Multilayers

“…Assuming the applicability of a one-dimensional Fick's law for this system, the diffusion coefficient of the acid from the film can be estimated from the initial slope of a plot of mass verses t 1/2 . Such analysis yields a value of 9.7 × 10 -14 cm 2 /s, in excellent agreement with the value of 8.0 × 10 -14 cm 2 /s measured by Honig using ellipsometry . As is readily seen in Figure , two time scales characterize the behavior of our film, a result that is also in agreement with previous observations put forth by Honig and de Koning .…”

“…The skeletonization process was investigated by monitoring the mass of film as a function of solvent immersion time. Previous researchers have determined that the process is equivalent, whether undertaken continuously or in intervals (i.e., continuous immersion for 1 h is equivalent to 6 10-min intervals or 12 5-min intervals) . As our quartz crystal microbalance is not configured to operate in solution, we took the latter approach.…”

A note on the use of ellipsometry for studying the kinetics of formation of self-assembled monolayers

“…Ellipsometry, a technique based on the principle of change in state of polarization of light on reflection from an optically flat surface (Azzam and Bashara 1977), is one of the most versatile and commonly used techniques for studying various processes such as the kinetics of SAM formation on metal surfaces (Tillman et al 1988;Bain et al 1989;Wasserman et al 1989), formation of multilayer Langmuir Blodgett films (Honig and De Koning 1976) and protein absorption in biological films (Cuypers 1983) to name a few. At very low film thickness, as would occur in the sub-monolayer and monolayer stages of SAM formation, the change in the ellipsometric angle ψ is well below the experimental uncertainty in angle measurement.…”

Skeletonization as a Probe of Interlayer Correlations in Langmuir−Blodgett Films

“…The kinetics of this skeletonization process and the optical constants of the resulting films have been previously studied. [1][2][3][4][5] However, the details of the mixing of acid and soap molecules and, hence, the structure of the skeletonized film have remained a mystery.…”

“…Since the films successfully skeletonized are prepared at a pH lower than necessary for full conversion of free acid to soap, it is reasonable to assume that the molecules removed by dissolution in benzene correspond to the free acid and that the molecules converted to soap remain in the film. The kinetics of this skeletonization process and the optical constants of the resulting films have been previously studied. − However, the details of the mixing of acid and soap molecules and, hence, the structure of the skeletonized film have remained a mystery.…”