Sm. Haight et al., In situ oxidation state profiling of nickel hexacyanoferrate derivatized electrodes using line-imaging Raman spectroscopy and multivariate calibration, J ELCHEM SO, 146(5), 1999, pp. 1866-1872
Reported is the use of line-imaging Raman spectroscopy for the in situ dete
rmination of oxidation state profiles in nickel hexacyanoferrate derivatize
d electrodes under potential control in an electrochemical cell. Line-imagi
ng Raman spectroscopy is used to collect 256 contiguous Raman spectra every
similar to 5 mu m from thin films (ca. 80 nm) formed by electrochemical de
rivatization of nickel electrodes. The cyanide stretching region of the Ram
an spectrum of the film is shown to be sensitive to iron oxidation state an
d is modeled by both univariate and multivariate correlations. Although bot
h correlations fit the calibration set well, the multivariate (principle co
mponent regression or PCR) model's predictions of oxidation state are less
sensitive to noise in the spectrum, yielding a much smoother oxidation stat
e profile than the univariate model. Oxidation state profiles with spatial
resolution of approximately 5 mu m are shown for a nickel hexacyanoferrate
derivatized electrode in reduced, intermediate, and oxidized states. In sit
u oxidation stare profiles indicate that the 647.1 nm laser illumination ph
oto-oxidizes the derivatized electrodes. This observation is confirmed usin
g photoelectrochemical methods. (C) 1999 The Electrochemical Society. S0013
-4651(97)05-063-5. All rights reserved.