Analysis of picosecond laser induced fluorescence phenomena in photosynthetic membranes utilizing a master equation approach

Paillotin, Guy; Swenberg, Charles E.; Breton, Jacques; Geacintov, Nicholas E.

doi:10.1016/s0006-3495(79)85320-5

Cited by 173 publications

(101 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A definitive treatment of the picosecond absorption recovery at 850 nm requires precise knowledge of the excitation flux, secure determination of the long time decays, and scans at pump intensities lower than those used here. Nevertheless, (20). The values of z, the average number of excitations per domain, and the value of y/2, the annihilation rate constant, required to fit our data are very different from those previously determined for the B800-850 complexes of Rb.…”

contrasting

confidence: 88%

Femtosecond dynamics of energy transfer in B800-850 light-harvesting complexes of Rhodobacter sphaeroides.

Trautman

Shreve

Violette

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

We report femtosecond transient absorption studies of energy transfer dynamics in the B800-850 lightharvesting complex (LHC) of Rhodobacter sphaeroides 2.4.1. For complexes solubilized in lauryldimethylamine-N-oxide (LDAO), the carotenoid to bacteriochlorophyll (Bchl) B800 and carotenoid to Bchl B850 energy transfer times are 0.34 and 0.20 ps, respectively. The B800 to B850 energy transfer time is 2.5 ps. For complexes treated with lithium dodecyl sulfate (LDS), a carotenoid to B850 energy transfer time of c0.2 ps is seen, and a portion of the total carotenoid population is decoupled from Bchl. In both LDAO-solubilized and LDS-treated complexes an intensity-dependent picosecond decay component of the excited B850 population is ascribed to excitation annihilation within minimal units of the LHC.The B800-850 light-harvesting complex (LHC) serves as the principal antenna complex in many purple photosynthetic bacteria (1) and has been extensively studied in Rhodobacter sphaeroides and related genera (1-12). The B800-850 LHC contains bacteriochlorophyll (Bchl) and carotenoid pigments in a ratio of 2:1 (2, 3). The Bchl is partitioned between two binding sites; the Qy absorption of B800 is near 800 nm, that of B850 is near 850 nm. In B800-850 solubilized in lauryldimethylamine-N-oxide (LDAO), referred to as B800-850/ LDAO, both absorptions are present; in B800-850 treated with lithium dodecyl sulfate (LDS), referred to as B800-850/LDS, the 800-nm absorption is absent (4, 5). Models for the structure of the B800-850 complex suppose the complex to be composed of replications of a minimal pigmentpolypeptide unit (6, 7). The minimal unit of ref. 6 contains four B850, two B800, and three carotenoid molecules. Two of the carotenoids are coupled only to B850 molecules and the third carotenoid is coupled only to B800 molecules.Previous work has provided some understanding of singlet energy transfer processes in B800-850 LHCs. In B800-850/LDAO isolated from Rb. sphaeroides 2.4.1, total carotenoid to B850 energy transfer efficiency is 95% ± 5% (4, 6). At 4 K, 15-25% of the carotenoid excitations are transferred to B800 with subsequent, nearly 100% efficient, B800 to B850 energy transfer; the remaining carotenoid excitations are transferred directly to B850 (8). Measurements of the B800 to B850 transfer have put the time at (i) 1-2 ps at 77 K and <1 ps at 295 K as determined by picosecond transient absorption spectroscopy (9) and (ii) :3.3 ps at 4 K as calculated from B800 fluorescence emission measurements (8). For B800-850/LDS the total carotenoid to B850 energy transfer efficiency is only 72% ± 3% (4, 6). The dynamics of carotenoid to Bchl energy transfer have been studied by picosecond transient absorption in two strains of Rhodopseudomonas acidophila revealing carotenoid to Bchl transfer times of :'5 ps (10) and ==3 ps (11). The mechanism of carotenoid to Bchl singlet energy transfer is thought to be exchange coupling (13) with transfer occurring from an energetically low-lying carotenoid electronic state analogous t...

show abstract

contrasting

confidence: 88%

Femtosecond dynamics of energy transfer in B800-850 light-harvesting complexes of Rhodobacter sphaeroides.

Trautman

Shreve

Violette

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…At the pump intensity of 2 mJ · cm -2 used in the TA experiments, the average number of excitations/chromophore can be estimated to amount to p ) 0.08. The probability, P x , to have x excitations/system is given by the binomial distribution: 76,77 …”

Section: Discussionmentioning

confidence: 99%

Ultrafast Photoinduced Charge Separation in Naphthalene Diimide Based Multichromophoric Systems in Liquid Solutions and in a Lipid Membrane

et al. 2008

View full text Add to dashboard Cite

The photophysical properties of multichromophoric systems consisting of eight red or blue naphthalene diimides (NDIs) covalently attached to a p-octiphenyl scaffold, as well as a blue bichromophoric system with a biphenyl scaffold, have been investigated in detail using femtosecond time-resolved spectroscopy. The blue octachromophoric systems have been recently shown to self-assemble as supramolecular tetramers in lipid bilayer membranes and to enable generation of a transmembrane proton gradient upon photoexcitation (Bhosale, S.; Sisson, A. L.; Talukdar, P.; Fürstenberg, A.; Banerji, N.; Vauthey, E.; Bollot, G.; Mareda, J.; Röger, C.; Würthner, F.; Sakai, N.; Matile, S. Science 2006, 313, 84). A strong reduction of the fluorescence quantum yield was observed when going from the single NDI units to the multichromophoric systems in methanol, the effect being even stronger in a vesicular lipid membrane. Fluorescence up-conversion measurements reveal ultrafast self-quenching in the multichromophoric systems, whereas the formation of the NDI radical anion, evidenced by transient absorption measurements, points to the occurrence of photoinduced charge separation. The location of the positive charge could not be established unambiguously from the transient absorption measurements, but energetic considerations indicate that charge separation should occur between two NDI units in the blue systems, whereas both an NDI unit and the p-octiphenyl scaffold could act as electron donor in the red system. The lifetime of the charge-separated state was found to increase from 22 to 45 ps by going from the bi-to the octachromophoric blue systems in methanol, while a 400 ps decay component was observed in the lipid membrane. This lifetime lengthening is explained in terms of charge migration that is most efficient when the octachromophoric systems are assembled as supramolecular tetramers in the lipid membrane. Furthermore, the average charge-separated state lifetime of the red system in methanol is even larger and amounts to 750 ps. This effect cannot be simply explained in terms of Marcus inverted regime as the driving force for charge recombination in the red system is only slightly larger than in the blue one. A better spatial separation of the charges in the red system stemming from the localization of the hole on the p-octiphenyl scaffold could additionally contribute to the slowing down of charge recombination.

show abstract

“…This interaction manifests itself in further shortening of the average excitation lifetime (see Fig. 1), the decrease in the fluorescence quantum yield (Paillotin et al 1979, van Grondelle 1985 as well as the decrease in the probability of excitation capture by RC (Mineev and Razjivin 1987).…”

Section: The Region Of High Intensities Singlet-singlet Annihilationmentioning

confidence: 99%

Picosecond processes in chromatophores at various excitation intensities

1991

View full text Add to dashboard Cite

The aim of this paper is to review and discuss the results obtained by fluorescence and absorption spectroscopy of bacterial chromatophores excited with picosecond pulses of varying power and intensity. It was inferred that spectral and kinetic characteristics depend essentially on the intensity, the repetition rate of the picosecond excitation pulses as well as on the optical density of the samples used. Taking the different experimental conditions properly into account, most of the discrepancies between the fluorescence and absorption measurements can be solved. At high pulse repetition rate (>10(6) Hz), even at moderate excitation intensities (10(10)-10(11) photons/cm(2) per pulse), relatively long-lived triplet states start accumulating in the system. These are efficient (as compared to the reaction centers) quenchers of mobile singlet excitations due to singlet-triplet annihilation. The singlet-triplet annihilation rate constant in Rhodospirillum rubrum was determined to be equal to 10(-9) cm(3) s(-1). At fluences >10(12) photons/cm(2) per pulse singlet-singlet annihilation must be taken into account. Furthermore, in the case of high pulse repetition rates, triplet-triplet annihilation must be considered as well. From an analysis of experimental data it was inferred that the singlet-singlet annihilation process is probably migration-limited. If this is the case, one has to conclude that the rate of excitation decay in light-harvesting antenna at low pumping intensities is limited by the efficiency of excitation trapping by the reaction center. The influence of annihilation processes on spectral changes is also discussed as is the potential of a local heating caused by annihilation processes. The manifestation of spectral inhomogeneity of light-harvesting antenna in picosecond fluorescence and absorption kinetics is analyzed.

show abstract

Analysis of picosecond laser induced fluorescence phenomena in photosynthetic membranes utilizing a master equation approach

Cited by 173 publications

References 20 publications

Femtosecond dynamics of energy transfer in B800-850 light-harvesting complexes of Rhodobacter sphaeroides.

Femtosecond dynamics of energy transfer in B800-850 light-harvesting complexes of Rhodobacter sphaeroides.

Ultrafast Photoinduced Charge Separation in Naphthalene Diimide Based Multichromophoric Systems in Liquid Solutions and in a Lipid Membrane

Picosecond processes in chromatophores at various excitation intensities

Contact Info

Product

Resources

About