We have successfully evaluated and incorporated ferrocene-based polymers as sensing elements in a novel tapered optical fiber device. State-of-the art performance was observed for these devices. We have shown that a small variation in the refractive index of the cladding has a direct influence on the transmission characteristic of the tapered region. The responses of several tapers to ammonia, carbon dioxide, and nitrous oxide were examined. Several sensors with different sensitivities were fabricated by tuning their beat length during the tapering process. Ellipsometry was used to characterize the change in the refractive index. Reusability and selectivity of several tapers were also investigated. A novel, computer based, analysis has been developed to predict the behavior of these devices. A reasonable agreement was obtained between the experiments and the theory.
The study of the electrical properties of these ferrocene-based polymers is the second major contribution of this research. The electrical conductivity of these materials was investigated by means of iodine doping. The polymers were all made by thermal ring opening of the corresponding [1]-silylene-ferrocenophane, [Special characters omitted.] and [Special characters omitted.] and n -Bu 2 . The thin films were cast from toluene solution. The UV, Raman and Mössbauer spectroscopy were the techniques used to study these materials. The changes in the UV and Raman spectra of the polymer films upon iodine doping point to the formation of I 3 - and I 5 - anions, depending in the amount of iodine present in the film. The changes in the spectroscopic data upon doping confirm the partial or complete oxidation of ferrocenylene groups into ferrocenium cations. The reversibility of the doping was studied and shown to depend upon the amount of initial doping and film thickness. Treatment of the doped films with ammonia results in partial regeneration of the original polymer, but some degradation is observed.
