University of Illinois Urbana-Champaign

Fluorescent Probes and Optical Standing Waves for Spatial Characterization of Polymer Modified Electrodes

Laley, Steven Lawrence

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Description

Title
Fluorescent Probes and Optical Standing Waves for Spatial Characterization of Polymer Modified Electrodes
Author(s)
Laley, Steven Lawrence
Issue Date
1986
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Analytical
Abstract
  • This project has addressed the considerations necessary and the work involved in using fluorescent probes with optical standing waves for observation of dimensional changes of polymer modified electrodes. A fundamental goal of this study has been to evaluate the efficiency of fluorescent probe layers to determine in situ film thickness variations of thin polymer films on electrodes.
  • A suitable assembly was constructed consisting of a thin (100-350 nm) poly(styrene sulfonate) film spin-coated onto a nickel film electrode. A fluorescein isothiocyanate-labelled poly(vinyl alcohol) probe layer was synthesized and spin-coated over the poly(styrene sulfonate) layer to complete the assembly.
  • Interference patterns were established in the polymer layer due to reflected light at the metal surface--causing optical standing waves in the electric field of an incident excitation beam. Dimensional changes in the polymer layer were monitored by observing anti-nodal positions in the excitation or emission spectrum of the probe layer. These patterns are due to the presence of a high electric field in the vicinity of the probe layer, and affect the fluorescent intensity observed. The wavelength at which the anti-nodal position occurs is directly proportional to the distance between the electrode (mirror) and the fluorescent probe layer.
  • Swelling studies with neat, 6 million molecular weight PSS films in contact with a H(,2)O/CH(,3)CN solution indicate that the polymer layer's geometric thickness increases linearly with H(,2)O concentration after a threshold concentration of approximately 6 percent H(,2)O has been added to the acetonitrile.
  • In situ film thickness measurements of PSS films containing electrostatically bound Ru(bpy)(,3)('2+) and Os(bpy)(,3)('2+) centers indicate small thickness variations (less than 5 percent). The thickness variations exhibited during oxidation and reduction of the centers were consistent with previous electrochemical studies of the two systems and were self-consistent with a model developed to describe the assembly.
Graduation Semester
1986
Type of Resource
text
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http://hdl.handle.net/2142/70318

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