Raman based pH measurements with polyaniline

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Lindfors T, Ivaska A
Publisher: ELSEVIER SCIENCE SA
Publication year: 2005
Journal: Journal of Electroanalytical Chemistry
Journal acronym: J ELECTROANAL CHEM
Volume number: 580
Issue number: 2
Start page: 320
End page: 329
Number of pages: 10
ISSN: 1572-6657
eISSN: 1873-2569


Abstract

The reversible acid-base equilibrium between the emeraldine salt (ES) and the emeraldine base (EB) form of thin electropolymerized films of polyaniline (PANI) has been studied between pH 2 and 9 with in situ Raman spectroscopy using the 514, 633 and 780 nm laser excitation wavelengths. The electropolymerization of PANI was done with cyclic voltammetry in a flow cell from a solution consisting of 50 mM aniline and 1.0 M HCl. It is shown that the Raman signal of the C=N stretching vibration at 1439 cm(-1), originating from the quinoid units of the EB form, can be used for pH measurements between pH 3 and 6 with the 633 nm laser. This vibration is strongly resonance enhanced by the 633 nm laser and its intensity grows therefore considerably in the pH interval where the ES-EB transition mainly takes place (pH 3-6). The influence of the film conditioning pH was also studied as well as the reproducibility of the Raman spectra when pH was changed several times from pH 6 to 3.


Keywords

514 nm, 633 nm, 780 nm, conducting polymer, emeraldine base (EB), emeraldine salt (ES), pH measurements, polyaniline, Raman spectroscopy

Last updated on 2019-20-10 at 04:03