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Publications (37)
The keto-carotenoid deinoxanthin, which occurs in UV-resistant bacterium Deinococcus radiodurans, has been investigated by ultrafast time-resolved spectroscopic techniques. We have explored excited-state properties of deinoxanthin in solution and bound to the S-layer Deinoxanthin Binding Complex (SDBC), a protein complex important for UV resistance...
Octadecaoctaenal is a psittacofulvin pigment associated with the bright red coloration of parrots. It consists of a linear polyene chain terminated by an aldehyde group and therefore provides an opportunity to examine the fundamental factors controlling the excited state ordering and dynamics of polyenals. Steady-state and ultrafast time-resolved s...
Fluorescence resonance energy transfer (FRET) under in vivo conditions is a well-established technique for the evaluation of populations of protein bound/unbound nucleic acid (NA) molecules
or NA hybridization kinetics. However, in vivo FRET has not been applied to in vivo quantitative conformational analysis of NA thus far. Here we explored parame...
a b s t r a c t Imaging of small objects such as single molecules, DNA clusters and single bacterial cells is problematic not only due to the lateral resolution that is obtainable in currently existing microscopy but also, and as much fundamentally limiting, due to the lack of sufficient axial depth of focus to have the full object focused simultan...
Spectra of individual silicon nanocrystals within porous Si grains are studied by the wide-field imaging microspectroscopy and their ON–OFF blinking is detected by the confocal single-photon-counting microscopy. Observed spectral and blinking properties comprise all features reported before in differently prepared single Si nanocrystals (SiNCs). Fo...
Ultrastructure of plant chloroplasts was studied by a single-molecule spectroscopy setup at a temperature of 77 K exploring spatial location of photosystems. Two chloroplast thylakoid membrane regions were visualized by fluorescence microscopy and detected at different wavelengths. The size of these regions and the spatial resolution of the microsc...
Irradiance power and spectral composition as well as nutrient availability strongly influence differentiation of filamentous cyanobacteria. When monitoring the life cycle of Calothrix elenkinii Kossinsk., we found that low nitrogen concentration and growth under green light led to a transient appearance of high-fluorescence cells that rapidly bleac...
Photosynthetic organisms exposed to a dynamic light environment exhibit complex transients of photosynthetic activities that are strongly dependent on the temporal pattern of the incident irradiance. In a harmonically modulated light of intensity I approximately const.+sin(omegat), chlorophyll fluorescence response consists of a steady-state compon...
Results of low temperature fluorescence and spectral hole burning experiments with whole cells and isolated chlorosomes of the green sulfur bacterium Chlorobium limicola containing BChl c are reported. At least two spectral forms of BChl c (short-wavelength and long-wavelength absorbing BChl c) were identified in the second derivative fluorescence...
Net photosynthetic rate (PN), productivity and the first phases of the fluorescence induction curve were investigated in leaves of two potato cultivars
exposed to water stress. Water stress applied to potato plants at the beginning of their development (planting-bud formation)
increased productivity but decreased PN and variable fluorescence (Fv) o...
Low-temperature fluorescence and fluorescence excitation spectra of H 2 -tetra-4-tert-butyl phthalocyanine Langmuir-Blodgett films consisting of well-ordered phthalocyanines in domains and off-domain phthalocyanine molecules in random-oriented positions were measured. Persistent spectral hole burning was applied to study the role of fast excited en...
We observe a blue shift of the porous silicon photoluminescence peak with decreasing temperature in the range 305-180 K. Further, we study two-photon absorption (TPA) in porous silicon at 300 K through the luminescence excitation spectrum. The TPA shows an exponential tail with onset at 2hnu approximately 2.4 eV. This shape can be ascribed to poten...
High spectral selectivity of hole burning in fluorescence spectra was used to study excited energy transfer in the CP 43 chlorophyll-protein complex of core antenna of photosystem II of Synechococcus. The observed energy transfer time is 7.6 +/- 1.1 ps. The phenomenon of laser-induced hole filling was studied and explained in terms of energy transf...
Results of low temperature fluorescence and spectral hole burning experiments with whole cells and isolated chlorosomes of the green sulfur bacterium Chlorobium limicola containing BChl c are reported. At least two spectral forms of BChl c (short-wavelength and long-wavelength absorbing BChl c) were identified in the second derivative fluorescence...
Results of persistent hole burning fluorescence spectroscopy of green sulphur photosynthetic bacterium Chlorobium limicola are presented. Homogeneous spectral linewidths were determined from holewidths burned into inhomogeneously broadened NIR fluorescence spectra of chlorosomal bacteriochlorophyll-c at 1.8-4.2 K. The determined excited state relax...
The hole burning method was applied to the study of the photophysical properties of H 2 -tetra-4-tert-butyl phthalocyanine (H 2 -TTBPc) Langmuir-Blodgett film. The fluorescence spectra of this film together with the hole profile and the holewidth temperature dependence are presented. The influence of the fast excited state energy transfer on the pr...
Low temperature hole burning excitation fluorescence spectra of a set of uroporphyrin I esters in amorphous (chloroform) matrix are presented. The hole burning spectra were excited within the region of the O-O S1 ? S0 transition and measured in the temperature range 1.5 - 4.3 K. From the fluence the values of homogeneous linewidths were determined....
Results of persistent spectral hole burning in fluorescence spectra of photosystem II core antenna complexes CP 43 and CP 47 are presented. The holewidths (extrapolated to zero burning fluence) yield the excited state population decay times T1 which are influenced by fast energy transfer within the antenna complexes. The obtained T1 values range be...
The hole burning technique was applied in fluorescence excitation spectra of free base tetra-4-tert-butyl phthalocyanine multilayer Langmuir-Blodgett films. Persistent holes were burnt into the spectral region near 615 nm (attributed to the absorption of domains of parallel molecules) and detected near 700 nm at the O-O fluorescence band (attribute...
Hole burning spectroscopy is a low temperature high resolution technique based OD the removal of inhomogeneous broadening of optical spectra of guest molecules in solid matrices. The removal is achieved by narrow band laser irradiation of the sample, followed by photoinduced transformation of spectrally selected homogeneous packet of guest molecule...
The persistent spectral hole burning technique was applied to the fluorescence spectra of free base tetra-4-tert-butyl phthalocyanine and chlor-aluminium tetra-4-tert-butyl phthalocyanine multilayer Langmuir-Blodgett films. Resonant zero phonon holes were burnt into the O-O fluorescence band near 700 nm at 4.2 K. A set of red shifted off-resonant h...
The low-temperature fluorescence and fluorescence excitation hole-burning (HB) spectra at 4.2 K of uroporphyrin in amorphous (chloroform) matrix are presented. Persistent photochemical holes were burnt using both pulse and cw ring dye lasers within the region of OO transition. The HB mechanism was attributed to the tautomerisation of two inner pro...
Persistent spectral hole-burning fluorescence spectra of photosystem II core antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect...
Uroporhyrin, like other natural porphyrins such as coproporphyrin or protoporphyrin, is an important intermediate occurring in the metabolic pathway to protoheme. These porphyrins are important indicators of pathogenic states in an organism. Luminescence spectra of these molecules consist of (≈ 100 cm –1 ) broad bands due to an inhomogeneous broade...
Chlorobium limicola is a green sulfur photosynthetic bacteria. Its light harvesting system consists of huge extra-membrane ellipsoidal structures (100-150 nm long and 30-40 nm in diameter) called chlorosomes. Each chlorosome contains several thousands of bacteriochlorophyll-c (BChl-c) molecules (organized in long rod-like pigment-protein complexes)...
Photosystem II core antenna of blue-green algae Synechococcus isolated in gel was studied by optical hole burning spectroscopy at 4.2 K. Persistent holes were burned into fluorescence spectra throughout the region 680-696 nm. The hole width extrapolated to zero burning fluence yielded a value 1.0 +/- 0.2 cm-1. A theoretical interpretation of the ho...
This paper reports transient and persistent hole-burning of photosynthetically active as well as chemically reduced and heat inactivated photosystem II particles isolated from cyanobacteria. Transient spectra of active and non-active particles are significantly different. For both, the possible origin of the bottle-neck state is discussed. Persiste...
The persistent spectral hole burning technique has been applied to free base and central metal tetraphenylporphyrins with different substituents. The upper limits of the singlet-singlet homogeneous widths determined from the observed persistent holes have been correlated with the fluorescence lifetimes at low temperatures. Hole burning kinetics and...
Persistent and transient fluorescence hole-burning spectra of both higher plants and blue-green algae were measured to study the role of structural and functional properties of photosynthetic materials prepared by means of different biochemical methods: intact cells, thylakoide membranes, photosystem II particles and isolated antenna pigments. The...
Phthalocyanine Lanngmuir Blodgett (LB) films represent ultra thin monomolecular layers with molecules in tight contact. Most of the phthalocyanine molecules in LB films are ordered in domains where they occupy well defined (parallel) positions. There is also a minority of non-ordered molecules in off-domain positions in LB films. This fact is well...
The application of hole burning spectroscopy (HB) in the study of photosynthetic systems offers an independent method for determining excited state lifetimes of particular chromophores. The rate constants of excitation energy transfer (EET) in photosynthetic antennae can be directly determined by time resolved fluorescence spectroscopy. For most ba...
