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Owing to the strong dependence of the resistivity on the dopant concentration, nonuniformity across the thickness of a sample leads to an apparent anisotropy in the resistivity (measured parallel to and perpendicular to the plane of the film). Thus the magnitude of the apparent anisotropy (for nonoriented samples) offers a convenient means for quantifying the degree of dopant nonuniformity in trans-(CH)". This technique is used to evaluate the uniformity achieved in [CH(AsF5)r]"by conventional vapor-phase doping as compared with the slow-doping technique developed earlier for susceptibility studies. Using samples which have been demonstrated in this manner to be uniform, we reexamine the semiconductor-metal transition. From the transport data, we find that the better the uniformity in the distribution of dopant, the more abrupt is the transition at y,~. 002. A generalized soliton picture, involving delocalized carriers, appears to be implied by the combination of optical, magnetic, and transport data.

Cyclic polarization measurements made on steel, iron oxalate-coated steel and polyaniline in a high pH solution and in the absence of chloride ions showed no tendency of the surface towards pitting corrosion. In all cases, the pitting potential was similar to the protection potential. Chlorides in the caustic solution caused significant pitting in the bare steel and slight pitting in the oxalate coated steel. The polyaniline coated-steel showed no pitting in the chloride-containing alkaline solution. Scratches through the polyaniline coating did not initiate pitting in the polyaniline coated steel surface when tested in the chloride-containing solutions. q

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