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Angular Dependence in Raman Spectroelectrochemistry for Conducting Polymer Films on Platinum Electrodeтезисы доклада
- Авторы: Nekrasov A.A., Gribkova O.L., Cabanova V.A., Iakobson O.D.
- Сборник: Abstracts of the 69th Annual Meeting of the International Society of Electrochemistry, 2 to 7 September 2018, Bologna, Italy
- Тезисы
- Год издания: 2018
- Место издания: The International Society of Electrochemistry Lausanne, Switzerland
- Первая страница: ise183133
- Аннотация: Raman spectroelectrochemistry is a powerful tool to monitor structural transformations during electrosynthesis and doping/dedoping of conducting polymers. However, laser beam used for excitation of Raman scattering passes several interfaces, where absorption, refraction and reflection processes may occur. These are: air/glass (the wall of spectroelectrochemical cell); glass/electrolyte; electrolyte/film (of conducting polymer); film/electrode. It is important that the film of conducting polymer changes its thickness, absorption and refraction during the electrosynthesis and doping/dedoping. Moreover, conducing polymer films are inhomogeneous consisting of conductive domains distributed in non-conductive matrix. The sizes of these domains are changing during doping/dedoping thus changing Rayleigh component in the total scattering. All these processes influence the shape of in situ Raman spectra and also are dependent on the incident angle of the laser beam. In the reduced state (at -0.2 V) the film of polyaniline (PANI) doped with poly(styrenesulfonic acid) (PSSA) is maximally transparent and exhibits an intensive vibration near 600 cm-1. Similar vibration, which can be assigned to Pt-O stretching due to oxygen adsorption, is observed on clean Pt immersed into deionized water without applying potential. So, in the reduced state Raman spectrum of the PANI-PSSA film is superimposed with that of Pt. At the same time, the latter can not be simply subtracted form the overall spectrum in accordance with common procedure as the vibrations on clean Pt are far more intensive. By increasing incident angle of the laser beam from 0 to 24 degrees one can minimize the intensity of 608 cm-1 vibration in the spectrum thus minimizing the influence of Pt substrate on the spectrum shape. At further increasing of the angle the 608 cm-1 vibration decreases down to negative values, which is possibly due to interaction of the incident, scattered and reflected beams in the multilayered structure of the electrode. Similar angular dependence is observed for 1618 cm-1 vibration usually ascribed to C-C stretching in benzenoid rings of PANI. These changes can not be attributed to any Raman resonance or surface enhancement phenomena indicating that 1618 cm-1 vibration is also superimposed with some signal from the substrate. So, by changing laser incident angle one can minimize the substrate influence on the spectrum shape without significant changes of characteristic Raman bands of the polymer under study. This study was supported by the Russian Fund for Basic Research (grants No.16-29-06423, 18-53-18009)
- Добавил в систему: Некрасов Александр Александрович