In-Situ Monitoring the Growth of Polypyrrole Films at Liquid/Solid Interface Using a Combination of Polarized Infrared Spectroscopy and Reflectance Anisotropy Spectroscopy

Polarized infrared reflection measurements in an ellipsometric set-up and reflectance anisotropy spectroscopy (RAS) were used for the first time for combined in-situ characterization of the electrochemical growth (potentiostatic pulse method) of thin polypyrrole (PPy) films on Si(110). Both methods can monitor material and thickness related changes during deposition and are shown as sensitive tools for studying time development of PPy growth under varying potential. In detail polarized infrared spectroscopy delivered information on the chemical structure of the as-deposited film and RAS gave information on the quality of the interface and deposition rate. The identified polymerisation mechanism is in agreement with literature and valid for all times of deposition. For deposited films rough surfaces and partially inhomogeneous thicknesses (35 +/- 10 nm and 120 +/- 10 nm) were found. At present state it is not possible to simulate the in-situ RAS and IR-spectra in simple coherent optical layer models. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.044210jes] All rights reserved.