A study of kinetics of adsorption of alkanethiols on gold using electrochemical impedance spectroscopy

The growth kinetics of self assembled monolayer of alkanethiols of differen t chain lengths and concentrations on an evaporated gold surface on mica ha s been studied in situ and in real time using electrochemical impedance spe ctroscopy. The interfacial capacitance obtained from the measurement of the imaginary component of impedance is used to calculate the surface coverage as a function of time. From this data, rate constants of adsorption of alk anethiols have been measured in 0.1 M LiClO4 in ethanol solution. The resul ts show that the adsorption follows Langmuir kinetics at higher thiol conce ntration of 20 mu M and partial diffusion controlled kinetics at 5 mu M and lower. The adsorption at a concentration of 1 mM is so rapid that similar to 40% of the full monolayer is covered within the first 500 ms. (C) 2000 E lsevier Science Ltd. All rights reserved.