The Autolab Electrochemical Quartz Crystal Microbalance (EQCM) is an optional module for the Autolab PGSTAT which can be used to control a 6 MHz crystal oscillator. This technique can be used to perform electrogravimetric measurements with detection limits in the sub μg range.
Electrochemical Quartz Crystal Microbalance (EQCM)
Immersion of a quartz-crystal oscillator in an electrolyte solution, with simultaneous control of the applied potential of the overlaying metallic film enables simultaneous and in-situ determination of the mass variation in relation to surface charge-density associated with an electrosorption or electrodeposition process.
The technique has now become a valuable procedure in electrochemical surface science, complementary to charge evaluation procedures such as cyclic voltammetry (CV) and chronoamperometry. The applications of this technique range from metal plating to sensing of biological interactions. One of the applications for which the EQCM is particularly well suited is the underpotential deposition (UPD) of metallic adlayers on a gold coated crystal.
UPD is a phenomenon that occurs at potential values more positive than the Nernst equilibrium potential. This deposition mode, promoted by the existence of a metallic ion – surface interaction, often leads to the formation of a single atomic monolayer. The mass variation due to the formation of this monolayer is within the detection limit of the Autolab EQCM (range ~ 100 ng/cm2).
