Much larger changes in frequency with temperature are observed when QCM
crystals are immersed in liquids. This is due to the coupling of the shear mode
oscillation with the temperature dependent viscosity and density of the fluid- the
temperature coefficient due to this effect is ≈ 8Hz/ ºC for water. As a result, for
experiments in liquid phase in which the frequency is to be monitored at length,
the temperature must be controlled to at least 0.1°C, and preferably better. In
electrochemical experiments this is often achieved with temperature controlled
baths and jacketed cells. If temperature control is not possible or practical, it is
always good practice to wait at least 30 minutes before performing any accurate
measurements after the crystal comes in contact with a new medium and
measure the temperature of the solution around the crystal during the
experiments to perform temperature compensation. It is also common practice to
soak the mounted crystal(s) in the solution overnight before performing any
experiments to assure more stable readings.