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Replacement of the central Mg in chlorophylls by Ni opens an ultrafast (tens of femtoseconds time range) radiationless de-excitation path, while the principal ground-state absorption and coordination properties of the pigment are retained. A method has been developed for substituting the native bacteriochlorophyll a by Ni-bacteriochlorophyll a ([Ni]-BChl)(More)
Three substituted tetraazaporphyrins, octa-(4-tert-butylphenyl)-tetrapyrazinoporphyrazine, tetra-(4-tert-butyl)phthalocyanine and tetra-(4-tert-butyl)phthalocyanatomagnesium(t4-PcMg), were spectroscopically checked in solutions and liposomes with respect to suitability as potential sensitizers of a possible new start mechanism for photodynamic therapy (PDT)(More)
An intrinsic steady-state fluorescent system for bovine adrenodoxin has been developed to study the protein structure in solution and the processes involved in protein unfolding. Since mature Adx contains no natural Trp residue as internal probe, all of the aromatic amino acids, tyrosine at position 82 and four phenylalanines at positions 11, 43, 59 and 64,(More)
Stepwise two-photon excitation of chlorophyll a and b in the higher plant main light-harvesting complex (LHC II) and the minor complex CP29 (as well as in organic solution) with 100-fs pulses in the Q(y) region results in a weak blue fluorescence. The dependence of the spectral shape of the blue fluorescence on excitation wavelength offers a new approach to(More)
Prochlorococcus marinus SS120 is an ecologically important and biochemically intriguing marine cyanobacterium. In addition to divinyl chlorophylls (DV-Chls) a and b it possesses a particular form of phycoerythrin (PE), but no other phycobilins and therefore no complete phycobilisomes. Here, a spectroscopic characterisation of these DV-Chls and PE is(More)
Fluorescence of synthetic melanin in dimethyl sulfoxide has been excited by two-photon absorption at 800 nm, using 120 fs pulses with photon flux densities > or = 10(27) cm-2 s-1. The shortest main component of the three-exponential decay of fluorescence is 200 +/- 2 ps. The overall spectral shape is red-shifted with respect to the 400 nm excited(More)
Stepwise two-photon excited fluorescence (TPEF) spectra of the photosynthetic antenna complexes PCP, CP47, CP29, and light-harvesting complex II (LHC II) were measured. TPEF emitted from higher excited states of chlorophyll (Chl) a and b was elicited via consecutive absorption of two photons in the Chl a/b Qy range induced by tunable 100-fs laser pulses.(More)
The excited-state and lasing properties of 20-chloro-chlorophyll a in ether solution were compared to those of chlorophyll a. Desactivation parameters and cross-sections were obtained from non-linear absorption spectroscopy in combination with a phys-ice-mathematical methods package. The Cl substituent at C-20 (I) increases both intersystem crossing and(More)
Photosynthetically active pigments are usually organized into pigment-protein complexes. These include light-harvesting antenna complexes (LHCs) and reaction centers. Site energies of the bound pigments are determined by interactions with their environment, i.e., by pigment-protein as well as pigment-pigment interactions. Thus, resolution of spectral(More)
A quantitative (multistep) excitation-deactivation model of rose bengal (RB) has been developed which includes energy and electron transfer to oxygen and the possibility of photoproduct formation via higher excited triplet-singlet states. The model is based on previous measurements of non-linear absorption (NLA) and emission of RB with picosecond pulses at(More)