TEM on Individual Polyacetylene Fibrils

TEM-chamber and investigated using minimal dosis focussing (see below). For the TEM studies a Zeiss CEM 902 instrument was used. The whole preparation and the sample transfer 

For doping, the fibrils collected on a TEM mesh were trans-fered to a N2/I2 atmosphere for periods between one and ten minutes. The oxydized samples were then frozen by shock in liquid propane to stop possible further diffusion of the iodine within the fibrils. This also ensured that water possibly adsorbed on the fibrils was frozen amorphously and could not disturb the results by forming ice crystals. 

The extraction method presented above generally yields coarse pieces of the fibrillar surface and sometimes also individual fibrils (fig. 20) that cling to the Cu-rods of the net by adhesion or are frozen to the net when using cryo-preparation. 

A much better yield of individual fibrils is achieved by using commercially available nets coated by a C/formvar film. It is then possible to remove whole layers of fibrils from the sample (fig. 21). 

The individual fibrils do not show an internal structure and appear to be homogeneous. Only in some cases inclusions could be detected, indicating minor contaminations of the samples (fig. 22). Oxydation of single fibrils at ambient conditions in air did not lead to any changes in morphology except an increase of the dark spots just described, in accordance with previously performed SEM and TEM investigations of Epstein et al. /67/. 

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