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Two kinds of carbon nanotubes (CNTs) are selected to investigate hole-edge reactivity such as single-wall carbon nanotubes (SWNTs) and single-wall carbon nanohorns (SWNHs). The study is helpful to the understanding of hole-edge chemistry and would enable the production of well-designed carbonaceous materials with high functionality.

The electron-transfer process in mono- (NlP1) and multichromophoric (NlP3) triphenylamine core dendrimers carrying one and three peryleneimide electron accepter chromophores, are characterized using the combination of transient absorption and fluorescence experiments performed on a femtosecond to nanosecond time scale.

We demonstrate measurements of the efficiency of competing Forster-type energy-transfer pathways in single bichromophoric systems by monitoring simultaneously the fluorescence intensity, fluorescence lifetime, and the number of independent emitters with time. Peryleneimide end-capped fluorene trimers, hexamers, and polymers with interchromophore distances of 3.4, 5.9, and on average 42 nm, respectively, served as bichromophoric systems. Because of different energy-transfer efficiencies, variations in the interchromophore distance enable the switching between homoenergy transfer (energy hopping), singlet-singlet annihilation, and singlet-triplet annihilation. The data suggest that similar energy-transfer pathways have to be considered in the analysis of single-molecule trajectories of donor/acceptor pairs as well as in natural and synthetic multichromophoric systems such as light-harvesting antennas, oligomeric fluorescent proteins, and dendrimers. Here we report selectively visualization of different energy-transfer pathways taking place between identical fluorophores in individual bichromophoric molecules.

The time-resolved fluorescence kinetics of a first and a second generation dendrimer with peryleneimide chromophores at the rim and a terrylenediimide chromophore in the core were investigated. Analysis of the in-the-bay area substituted terrylenediimide model compound reveals subsets of molecules showing different relaxation pathways of the terrylene core.

A new study uses time-resolved fluorescence excitation spectroscopy to investigate the correlation between ground state conformation and excited state dynamics in a multichromophoric dendrimer.

A study of the role of longwave chlorophylls (Chl) in the energy migration in photosystem I (PSI) antenna of cyanobacteria was undertaken. The PSI trimeric and monomeric complexes were isolated from Spirulina, and stationary fluorescence emission and excitation spectra of PSI trimers and monomers were studied. The results showed that at least some of the longwave Chls occur at physiological conditions.

An ultrafast transient absorption spectroscopy analysis of Dronpa is done to determine the rate for the initial step of photoswitching from the neutral dark form to the intermediate which emerges to the anionic fluorescent form. It is shown that the acid-induced protonated form and the photoconverted protonated form are two different spectroscopic types.

The time-dependent spectral properties of a rigid, extended system consisting of three pentaphenylene units end-capped with perylene monoimide are studied by femtosecond transient absorption and single photon timing measurements. It is seen that quantum-chemical calculations performed on the system comprising of two pentaphenylene units end-capped with perylene monoimide support the experimental data.