Film structures, exposure effects

In the case of oxides, the exposure of a soft film, such as the as-deposited one, to a UV source is an alternative top-down process of inducing a densification of the inorganic matrix. This is a quite general effect whose extent depends on the chemical conditions of the synthesis, for instance, the degree of condensation and dimension of the oxide clusters in the sol. The pH of the sol is also very important because it also affects the extent of condensation of the film structure upon deposition. 

Figure 3.70 Room temperature optical absorption spectra of a 45(X)A-lhick film of neutral polypyrrole doped with at0.03 torr. (a) before exposure to I2, conductivity <10 6fl 1cm"1 (b) after 2 minutes I2 exposure, conductivity 4.8 ft em 1 (c) after 7 minutes exposure, conductivity 6,7 ft em 1 (d) after 22 minutes I2 exposure, conductivity 32ft cm The three structures seen on the low-energy side of (a) (c) arc possibly artifacts due to interference effects in the films. From Pfluger et at. (1983).

In the chemical generation, the time of exposure to formaldehyde had a dramatic effect on the structure of the silver particulate films formed under... 

PAni has a very complex structure and doping behaviour, see Fig. 9.6, and the spectra are sensitive to the polymer morphology, the level of oxidation and degree of protonation. This accounts for the considerable variation in tire spectra that have appeared in the literature. The effects are illustrated in Fig. 9.33 for various forms of the protonated salt. These spectra refer to dried films, electrochemically prepared at different electrode potentials, and subject to oxidation by exposure to air. This variation in preparation conditions means that the degrees of oxidation and protonation are not well defined, as evidenced by the pronounced differences in the spectra of the emeraldine prepared at the... 

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