Chapter

The Quartz Crystal Microbalance in Soft Matter Research

Part of the series Soft and Biological Matter pp 205-219

Date:

Homogeneous Semi-infinite Samples

  • Diethelm JohannsmannAffiliated withInstitute of Physical Chemistry, Clausthal University of Technology Email author 

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Abstract

The load impedance of a homogeneous, semi-infinite medium in contact with the resonator surface is equal to the material’s shear-wave impedance, which leads to the Gordon-Kanazawa-Mason result. For Newtonian liquids the QCM determines the viscosity-density product. If the density is known independently, one can infer the viscosity. The Gordon-Kanazawa-Mason result can be extended to viscoelastic media, in which case the (complex) viscosity is often converted to the complex shear modulus at MHz frequencies. The formulation can be extended to cover nematic liquid crystals, colloidal dispersions, interfaces with shallow surface roughness, and samples, which touch the resonator in the center, only.