The influence of the synthesis parameters on the mean characteristics of single-wall carbon nanotubes in soot produced by the laser vaporization of graphite has been analyzed using optical absorption spectroscopy. The abundance and mean diameter of the nanotubes were found to be most influenced by the furnace temperature and the cobalt/nickel catalyst mixing ratio. Via an analysis of the fine structure in the optical spectra, the existence of preferred nanotube diameters has been established and their related fractional abundance could be determined. The results are consistent with nanotubes located mainly around the armchair axis.

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We report on absorption and fluorescence of single crystals of the unsymmetrically substituted diacetylene TS/FBS during UV-photopolymerization and thermal polymerization. All the observed reaction intermediates have been identified as diradicals, carbenes and stable oligomers. We compare these results with the well-known diacetylene TS6. The quantum yield of the initiation step as well as the activation energy of the following dark reaction have been determined. Well-separated yellow zones are characteristic for TS/FBS crystals: An additional blue-shifted polymer absorption and a strong fluorescence are typical for these regions. We compare this phenomenon with other chromism effects found with polydiacetylenes and discuss its origin.

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