Electrochemical quartz microbalance with working mercury electrode for quantitative studies of monolayer adsorption

The preparation and use of electrochemical quartz microbalance (EQCM) for q uantitative measurement of adsorbed mass is described. The thickness of mer cury film cannot exceed 20 nm. Best results are achieved when mercury is de posited on platinum at negative potentials, from -0.4 to -0.5 V versus Ag \ AgCl \ KClsat. At greater thickness, transformation of mercury films into less densely populated and larger droplets can be triggered by various surf ace perturbations. This leads to a deviation from linearity in the dependen ce of added mass on the frequency change. The suitability of a mercury coat ed EQCM has been demonstrated by measurements in lead(II) and thallium(I) c ontaining solutions. (C) 2000 Elsevier Science B.V. All rights reserved.