Simultaneous monitoring and evaluation of current and mass transients withthe QCMB in the millisecond range

An experimental set-up is described which allows the simultaneous recording of current and mass transients with millisecond resolution by using 5 MHz quartz resonators operated in a liquid environment. At the same time a mass resolution of a few nanograms is realized. It is demonstrated that this se t-up allows the application of fast potential pulses to electrohemically de posit/strip copper adlayers. The results proved that the obtained frequency response of the QCMB of 1 ms due to a sudden mass change has to be regarde d as an upper limit and is independent on the type of oscillator circuit us ed. Thus, this technique allows monitoring and evaluation of fast electrode processes such as copper deposition/stripping by comparing current and mas s transients recorded simultaneously. With this technique the integral sens itivity Ei for quartz resonators contacted with one face to a liquid was re investigated on the basis of charge and frequency changes associated with a bsolute mass changes spanning from the monolayer regime up to more than one hundred atomic layers. An unexpected sensitivity drop is observed in the l ower monolayer regime which is related to interfacial processes that occur due to shear elongations at the phase boundary solid/liquid.