We study excitation energy and charge transfer in small aggregates of chirality enriched carbon nanotubes by transient
absorption spectroscopy. Ground state photobleaching is used to monitor exciton population dynamics with sub-10 fs
time resolution. Upon resonant excitation of the first exciton transition in (6,5) tubes, we find evidence for energy
transfer to (7,5) tubes within our time resolution (< 10 fs). After pumping at high pump energies, free charge carriers are
produced via exciton scattering into the underlying continuum bands. We obtain clearly distinguished photoinduced
features in the visible spectral range, that allow for real-time tracing of charge carrier dynamics in carbon nanotubes on a
sub-picosecond time scale.
Using femtosecond pump probe spectroscopy with sub-20 fs resolution, we probe fundamental properties of the E11
exciton in (6,5) single walled carbon nanotubes, prepared by density gradient ultracentrifugation. From the initial
photobleaching signal, measured faster than any relaxation process, we obtain the one-dimensional size of the excitonic
wavefunction along the nanotube. Exciton decay is found pump-intensity dependent only at elevated pump intensities.
Numerical modelling of decay kinetics yields an exciton diffusion coefficient of about 0.1 cm^2/s. Anisotropy
measurements in highly purified samples show that there is virtually no depolarisation of the E11 bleach over 40 ps. A
photoinduced absorption (PA) band, blueshifted against the E11 bleach, shows only weak anisotropy.
Soluble titaniumoxophthalocyanines RmPcTiO with m = 4,8 and R = n-alkyl (C3-C7), trifluoromethyl, trifluoroethoxy, and the corresponding (t-butyl)4-naphthalocyanine are synthesized. The compounds are characterized spectroscopically, photochemically, and photoelectrically in solution and in vapor deposited or spin cast films. The results are compared to the insoluble parent compound PcTiO. According to positions of the electronic absorption bands, the films form amorphous and several crystalline phases depending on deposition and annealing conditions. All compounds are very weak electrical conductors in the dark, but much better ones upon irradiation. Conductivity increases also extremely upon oxygen doping. This effect is kinetically investigated and assigned to light assisted formation and dissociation of stable chemical complexes between Pc and 02. Complex formation is reversible to a high degree, but also irreversibly oxidized photoproducts are formed. Photoconductivity increases as function of chemical substituents in the series alkyl < BuNcTiO < PcTiO. The same series is also valid for stability against photooxidation in solution (as far as soluble) and in the films. For unannealed films of BuNcTiO and PcTiO the quantum yields for photooxidation in ambient atmosphere are in the order of φph = 10-6. After annealing, the yields of decomposition decrease by additional 1 -2 orders of magnitude.