Evidences for Adsorption of Heptyl Viologen Cation Radicals in Thin Deposition Layers on ITO Electrodes by Slab Optical Waveguide Spectroscopy

Yusuke AYATO  Akiko TAKATSU  Kenji KATO  Naoki MATSUDA  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.12   pp.1750-1754
Publication Date: 2006/12/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.12.1750
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Towards the Realization of Organic Molecular Electronics)
Category: Evaluation of Organic Materials
in situ,  slab optical waveguide (SOWG) spectroscopy,  adsorption phenomena,  heptyl viologen,  indium-tin-oxide (ITO) electrode,  

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In situ observations were mainly performed by using slab optical waveguide (SOWG) spectroscopy synchronized with potential step measurements to investigate the time dependent spectral change of the adsorbed heptyl viologen cation radicals (HV+・) in thin deposition layer on indium-tin-oxide (ITO) electrodes. Several absorption bands, which indicated a monomer and dimer of HV+・ were co-adsorbed on ITO electrode surface with a monolayer or a few layers deposition, were observed in UV-visible region. The time dependent spectra yielded some important molecular information for the adsorption phenomena of HV+・ on the electrode surface. All observed absorption bands disappeared completely when the electrode potential of -200 mV vs. Ag/AgCl was applied, which indicated the adsorbed HV+・ species were electrochemically reoxidized on the ITO electrode.