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Abstract: The lowest excited triplet (T1) state of tri-tert-butylpyridinotribenzotetraazaporphinatozinc (ZnPcPy) has been investigated using transient absorption and phosphorescence measurements. The excited-state absorption spectrum of the self-assembled dimer ((ZnPcPy)2) exhibits two sharp absorption bands (658 and 694nm) in the Q band region, in addition to triplet-triplet absorption at 500nm. This is the first observation of the Q band of the T1 phthalocyanine dimer. [Copyright &y& Elsevier]

Abstract: Picosecond transient absorption spectra of hypericin in solution have been recorded over the 350–850nm spectral range under excitation fluences, respectively, 3/4 and four times the saturation fluence. At low fluence only a weak sub-100ps decay component is detected, superimposed to the main nanosecond decay of the excited state. At high fluence a sub-10ps rising component, comparable to that of earlier reports, is observed. This novel observation is discussed within the context of the state-of-the-art theory of hypericin photophysics, involving intramolecular excited-state H atom transfer. A cooling process in the S1 state after biphotonic absorption is proposed as an alternative explanation. [Copyright &y& Elsevier]

Abstract: The optical absorption spectrum of the Ti8C12 and V8C12 Met-Cars is calculated using time-dependent density functional theory within a real-space, real-time scheme. Other ground-state quantities are also calculated, such as the ionization potential and the electronic affinity. The broad absorption features of the calculated absorption spectrum are related to experimental results about delayed ionization and delayed ion emission phenomena that have been observed in these structures. [Copyright &y& Elsevier]