Probing the Solid/Liquid Interface with the Quartz Crystal Microbalance

In this chapter we discuss the results of theoretical and experimental studies of the structure and dynamics at solid–liquid interfaces employing the quartz crystal microbalance (QCM). Various models for the mechanical contact between the oscillating quartz crystal and the liquid are described, and theoretical predictions are compared with the experimental results. Special attention is paid to consideration of the influence of slippage and surface roughness on the QCM response at the solid–liquid interface. The main question, which we would like to answer in this chapter, is what information on the structure and dynamics at the solid–liquid interface can be extracted from the QCM measurements. In particular, we demonstrate that the quartz crystal resonator acts as a true microbalance only if, in the course of the process being studied, the nature of the interface (its roughness, slippage, the density and viscosity of the solution adjacent to it, and the structure of the solvent in contact with it) is maintained constant. So far most of the QCM data were analyzed on a qualitative level only. The next step in QCM studies requires a quantitative treatment of the experimental results. Theoretical basis for the solution of this problem already exists, and has been discussed in this review. Joint experimental and theoretical efforts to elevate the QCM technique to a new level present a challenge for future investigators.