Theoretical Predictions for the Mechanical Response of a Model Quartz Crystal Microbalance to Two Viscoelastic Media: A Thin Sample layer and Surrounding Bath Medium.
Theoretical Predictions for the Mechanical Response of a
Model Quartz Crystal Microbalance to Two Viscoelastic
Media: A Thin Sample layer and Surrounding Bath Medium.
White, C. C.; Schrag, J. L.
Journal of Chemical Physics, Vol. 3, No. 24,
11192-11206, December 22, 1999.
quartz crystal microbalance; viscoelastic media; bath
medium; velocity; equations
Theoretical predictions are presented for the operating
characteristics of a quartz crystal microbalance (QCM)
system consisting of the crystal, an attached
viscoelastic sample layer, and a surrounding
viscoelastic bath medium. Predictions are given for the
spatial variation of ''particle'' velocity and velocity
gradient throughout the sample layer, for the
characteristic mechanical impedance acting on the
crystal surface due to the viscoelastic sample layer
plus surrounding bath medium, and for the resultant
changes in the resonance frequency of the QCM. Errors
introduced by employing the usual simple Sauerbrey-type
sample-layer-mass relationship, together with a constant
frequency offset to approximate the effect of the
viscoelastic bath medium, are explored. In general, the
viscoelastic properties of both the sample and bath
media can substantially affect the apparent thickness
(mass) of the sample layer if it is obtained by
employing the typical Sauerbrey-type approximation noted