Marcel Fuciman

University of South Bohemia in České Budějovice

The excited states of carotenoids have been a subject of numerous studies. While a majority of these reports target the excited state dynamics initiated by the excitation of the S2 state, the upper excited state(s) absorbing in the UV spectral region (denoted as SUV) has been only scarcely studied. Moreover, the relation between the SUV and Sn, the...

The functions of both (bacterio) chlorophylls and carotenoids in light-harvesting complexes have been extensively studied during the past decade, yet, the involvement of BChl a high-energy Soret band in the cascade of light-harvesting processes still remains a relatively unexplored topic. Here, we present transient absorption data recorded after ex...

We present the first examples of alkylated derivatives of the macropolyhedral boron hydride, anti-B18H22, which is the gain medium in the first borane laser. This new series of ten highly stable and colorless organic-inorganic hybrid clusters are capable of the conversion of UVA irradiation to blue light with fluorescence quantum yields of unity. T...

In the search for innovative new light sources, the discovery that solutions of the boron hydride anti-B18H22 generate photostable blue laser emission stands out in its significance as the first laser borane. Surprisingly, though, the laser performance of anti-B18H22 (~10 % efficiency) does not match the expectations based on its exceptional photop...

Recently a new family of carotenoproteins, homologs of the N-terminal domain of the orange carotenoid protein (NTD-OCP) have been identified in cyanobacteria. These homologs are called helical carotenoid proteins (HCPs) as they are all predicted to maintain the all-helical structure of the NTD-OCP and to bind carotenoid. Here, HCP2 and HCP3 isolate...

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...

We have developed an experimental set-up allowing to measure transient absorption spectra of carotenoids after two-photon excitation (2PE), thereby exciting the lowest excited state S 1 directly. We have compared 2PE and 1PE data of three carotenoids, lycopene, β-carotene, and neurosporene. Compared to ‘standard’ 1PE, the transient absorption spect...

To demonstrate the value of the multi-pulse method in revealing the nature of coupling between excited states and explore the environmental dependencies of S1 and ICT state equilibration, we performed ultrafast transient absorption pump-dump-probe and pump-repump-probe spectroscopies on fucoxanthin in various solvent conditions. The effects of pola...

We used ultrafast transient absorption spectroscopy to study excited-state dynamics of the keto-carotenoid fucoxanthin (Fx) and its two derivatives: 19’-butanoyloxyfucoxanthin (bFx) and 19’-hexanoyloxyfucoxanthin (hFx). These derivatives occur in some light-harvesting systems of photosynthetic microorganisms and their presence is typically related...

We have applied femtosecond transient absorption spectroscopy in pump-probe and pump-dump-probe regimes to study energy transfer between fucoxanthin and Chl a in fucoxanthin-Chl a complex from the pennate diatom Phaeodactylum tricornutum. Experiments were carried out at room temperature and 77 K to reveal temperature dependence of energy transfer....

The majority of life on Earth depends directly or indirectly on the sun as a source of energy. The initial step of photosynthesis is facilitated by light-harvesting complexes, which capture and transfer light energy into the reaction centers (RCs). Here, we analyzed the organization of photosynthetic (PS) complexes in the bacterium G. phototrophica...

Ultrafast transient absorption spectroscopy and single-wavelength anisotropy measurements were used to study the effect of isomerization on the excited-state properties of fucoxanthin in polar and non-polar solvents. The excitation wavelengths were 477 nm for the all-trans fucoxanthin and 333 nm and 477 nm, respectively, for the cis-fucoxanthin. Al...

Properties of the S1 state of neurosporene, spheroidene and lycopene were studied after excess energy excitation in the S2 state. Excitation of carotenoids into higher vibronic levels of the S2 state generates excess vibrational energy in the S1 state. The vibrationally hot S1 state relaxes faster when carotenoid is excited into the S2 state with e...

A quenching mechanism mediated by the orange carotenoid protein (OCP) is one of the ways cyanobacteria protect themselves against photooxidative stress. Here, we present a femtosecond spectroscopic study comparing OCP and RCP (red carotenoid protein) samples binding different carotenoids. We confirmed significant changes in carotenoid configuration...

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...

In order to estimate the possible structure of the unknown carbonyl carotenoid related to isofucoxanthin from Chromera velia denoted as isofucoxanthin-like carotenoid (Ifx-l), we employed steady-state and ultrafast time-resolved spectroscopic techniques to investigate spectroscopic properties of Ifx-l in various solvents. The results were compared...

Two carotenoids with aryl rings were studied by femtosecond transient absorption spectroscopy and theoretical computational methods, and the results were compared with those obtained from their non-aryl counterpart, β-carotene. Although isorenieratene has more conjugated C=C bonds than β-carotene, its effective conjugation length, Neff, is shorter...

We report on energy transfer pathways in the main light-harvesting complex of photosynthetic relative of apicomplexan parasites, Chromera velia. This complex, denoted CLH belongs to the family of FCP proteins and contains chlorophyll (Chl) a, violaxanthin, and the so far unidentified carbonyl carotenoid related to isofucoxanthin. The overall carote...

The major light-harvesting complex of Amphidinium (A.) carterae, chlorophyll-a–chlorophyll-c 2–peridinin–protein complex (acpPC), was studied using ultrafast pump-probe spectroscopy at low temperature (60 K). An efficient peridinin–chlorophyll-a energy transfer was observed. The stimulated emission signal monitored in the near-infrared spectral reg...

The excited-state dynamics, luminescence, and redox properties of a series of hexanuclear molybdenum cluster complexes, (nBu4N)2[Mo6X14] and (nBu4N)2[Mo6X8(CF3COO)6] (X = Cl, Br, or I), were investigated. Substitution of the apical halogen ligands for the trifluoroacetate ligands increased the oxidation potentials and induced a blue shift in the ab...

Excited-state properties of the carbonyl carotenoid monomeric and aggregated 8'-apo-β-carotenal were studied by means of femtosecond transient absorption spectroscopy. For 8'-apo-β-carotenal monomers, the polarity-dependent behavior characteristic of carotenoids with conjugated carbonyl group was observed. While in n-hexane the S1 lifetime of 8'-ap...

Plants are particularly prone to photo-oxidative damage caused by excess light. Photoprotection is essential for photosynthesis to proceed in oxygenic environments, either by scavenging harmful reactive intermediates or preventing their accumulation, in order to avoid photoinhibition. Carotenoids play a key role in protecting photosynthesis from th...

The spectroscopic properties and energy transfer dynamics of the protein-bound chlorophylls and xanthophylls in monomeric, major LHCII complexes, and minor Lhcb complexes from genetically altered Arabidopsis thaliana plants have been investigated using both steady-state and time-resolved absorption and fluorescence spectroscopic methods. The pigmen...

In carotenoids internal conversion between the allowed (S(2)) and forbidden (S(1)) excited states occurs on a sub-picosecond timescale; the involvement of an intermediate excited state(s) (S(x)) mediating the process is controversial. Here we use high time resolution (sub-20 fs) broadband (1.2-2.5 eV) pump-probe spectroscopy to study the solvent de...

The light-harvesting complex 2 from the thermophilic purple bacterium Thermochromatium tepidum was purified and studied by steady-state absorption and fluorescence, sub-nanosecond-time-resolved fluorescence and femtosecond time-resolved transient absorption spectroscopy. The measurements were performed at room temperature and at 10 K. The combinati...

Metallaborane compounds containing two adjacent metal atoms, [(PMe(2)Ph)(4)MM'B(10)H(10)] (where MM' = Pt(2), 1; PtPd, 7; Pd(2), 8), have been synthesized, and their propensity to sequester O(2), CO, and SO(2) and to then release them under pulsed and continuous irradiation are described. Only [(PMe(2)Ph)(4)Pt(2)B(10)H(10)], 1, undergoes reversible...

Photosynthetic reaction centers (RC) convert light into electrical potential via a series of electron transfers between protein-bound, redox-active cofactors. Direct voltammetry was used to characterize the RC protein from Rhodobacter sphaeroides and mutants with focus on the primary electron donor (P) cofactor. Cyclic voltammetry (CV) and square w...

Transient absorption spectroscopy, cyclic voltammetry, and DFT calculations were used to describe charge transfer processes in a series of 5,10,15,20-tetrakis(N-methylpyridinium-n-yl) porphyrins (TMPyPn, n = 4,3,2) and TMPyPn/p-sulfonatocalix[m]arene (clxm, m = 4,6,8) complexes. Excitation of TMPyPn is accompanied by an increasing electron density...

A peripheral light-harvesting complex from the aerobic purple bacterium Roseobacter (R.) denitrificans was purified and its photophysical properties characterized. The complex contains two types of pigments, bacteriochlorophyll (BChl) a and the carotenoid (Car) spheroidenone and possesses unique spectroscopic properties. It appears to lack the B850...

The peridinin-chlorophyll a-protein (PCP) is a light-harvesting pigment-protein complex found in many species of marine algae. It contains the highly substituted carotenoid peridinin and chlorophyll a, which together facilitate the transfer of absorbed solar energy to the photosynthetic reaction center. Photoexcited peridinin exhibits unorthodox sp...

Numerous femtosecond time-resolved optical spectroscopic experiments have reported that the lifetime of the low-lying S(1) state of carbonyl-containing polyenes and carotenoids decreases with increasing solvent polarity. The effect becomes even more pronounced as the number of double bonds in the conjugated π-electron system decreases. The effect h...

Chlorophyll (Chl) a/b-binding proteins from Prochlorothrix hollandica known as Pcb antennae were studied by femtosecond transient absorption technique to identify energy transfer rates and pathways in Pcb and Pcb-PS I complexes. Carotenoids transfer energy to Chl with low efficiency of approximately 25% in Pcb complexes. Interestingly, analysis of...

We present a study of excited-state dynamics of water-soluble carbonyl carotenoids, crocin, norbixin, and astalysine in solvents with different polarity. While no polarity effects were observed in 2-propanol and methanol, polarity-induced lifetime shortening has been detected in water. For crocin and astalysine the S1 lifetime decreases from 135ps...

Steady-state and femtosecond time-resolved transient absorption spectra of diadinoxanthin and diatoxanthin were measured in the visible and near-infrared (NIR) regions at 293K. The difference in energy between the visible S0→S2 transitions from the steady-state absorption measurements and the S1→S2 transitions observed in the transient absorption s...

Excited-state properties of aryl carotenoids, important components of light harvesting antennae of green sulfur bacteria, have been studied by femtosecond transient absorption spectroscopy. To explore effects of the conjugated aryl group, we have studied a series of aryl carotenoids with conjugated phi-ring, chlorobactene, beta-isorenieratene and i...

Effects of introducing a carbonyl group and its position in the conjugated system of carotenoids were studied by means of femtosecond time-resolved spectroscopy. We have compared four naturally occurring carotenoids with comparable structures, beta-carotene, echinenone, canthaxanthin and rhodoxanthin, which differ in the number and position of conj...

The role of the B800 in energy and electron transfer in LH2 complexes has been studied using femtosecond time-resolved transient absorption spectroscopy. The B800 site was perturbed by application of lithium dodecyl sulfate (LDS), and comparison of treated and untreated LH2 complexes from Rhodobacter sphaeroides incorporating carotenoids neurospore...

High voltage pulse electrical discharges in water solutions have been studied using different geometries of electrodes. It was demonstrated that discharges in all electrode congurations used (needle - plate, coaxial composite anode - tubular cathode and coaxial pinhole anode - tubular cathode) produce plasmas with very similar parameters. Plasma el...

A novel method for generation of focused shock waves based on multi-channel partial electrical discharges in water with an increased conductivity has been developed. The multi-channel discharge is formed on a composite anode consisting of a metallic electrode covered by a thin porous ceramic layer. Two versions of the generators have been realized....

A new driver of the fast capillary discharge is designed. It consists of the Marx generator and radial Blumline pulse forming line. Such a geometry enables axial access to both capillary ends ("transparent capillary"). This substantially simplifies the experiments (adjustment, monitoring, applications). The designed apparatus is capable to reach th...

A novel method for generation of focused shock waves in water has been developed. A cylindrical pressure wave created by a high voltage multi-channel discharge in water with an increased electrical conductivity is focused by a metallic parabolic reflector. The discharge is formed on a composite anode consisting of a cylindrical metallic electrode c...