The measurement principle
The Quartz Crystal Microbalance (QCM) measures the total mass of the film. As molecules adsorb and desorb, the total mass loading of molecules in the film can be inferred from the QCM response. The QCM is non-selective, that is, it responds to both polar and non-polar molecules.
The interdigitated electrode (IDE) capacitor measures the dielectric change of the sorbent film. This change is caused by the adsorption and desorption of polar molecules only such as water.
The sorbent-coated QCM and IDE are placed together in an environmental chamber where temperature, pressure, humidity, and gas composition are precisely controlled.
Since the IDE is only sensitive to polar molecules such as water, and the QCM is sensitive to all adsorbed molecules, the difference yields competitive adsorption of non-polar molecules such as CO2. This is how we make direct measurements of CO2/H2O competitive adsorption.
What about sample prep?
We are experts in turning powders into thin films. Send us your powder and we take it from there!
Contact us