Picosecond exciton annihilation in photosynthetic systems

Campillo, A. J.; Shapiro, S. L.; Kollman, V.H.; Winn, K. R.; Hyer, R.C.

doi:10.1016/s0006-3495(76)85666-4

Cited by 102 publications

(40 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Each regime has its value in revealing the nature of energy migration through the PA, and it appears as if light with longer pump durations is able to probe deeper into the long succession of steps that ultimately leads to stable charge separation and stored energy [3]. Picosecond pump sources, for example, do not probe the PA at all, reporting only the singlet lifetime of (Chlorophyll) Chl antenna [4][5][6], perhaps even before any energy is transferred to the PA. Nanosecond pump sources, used in the work presented here, do reveal initial traversal of the pump energy from the Chl-a as "light antenna" into the PA, and allow for monitoring the early attempts of the PA at charge separation [7,8]. The photosynthetic reactions in duced with these short pump pulses, however, are unstable and fluorescence results from their rever sal, as seen in Ref.…”

Section: Introductionmentioning

confidence: 99%

Observation of nanosecond laser induced fluorescence of in vitro seawater phytoplankton

et al. 2008

View full text Add to dashboard Cite

Seawater has been irradiated using a train of 70 ns flashes from a 440 nm laser source. This wavelength is on resonance with the blue absorption peak of Chlorophyll pigment associated with the photosystem of in vitro phytoplankton. The resulting fluorescence at 685 nm is instantaneously recorded during each laser pulse using a streak camera. Delayed fluorescence is observed, yielding clues about initiation of the photosynthetic process on a nanosecond time scale. Further data processing allows for determination of the functional absorption cross section, found to be 0:0095 Å 2 , which is the first reporting of this num ber for in vitro phytoplankton. Unlike other flash-pump studies of Chlorophyll, using a LED or flashlamp based sources, the short laser pulse used here does not reveal any pulse-to-pulse hysteresis (i.e., variable fluorescence), indicating that the laser pulses used here are not able to drive the photosynthetic process to completion. This is attributed to competition from a back reaction between the photoexcited photo system II and the intermediate electron acceptor. The significance of this work as a new type of deploy able ocean fluorimeter is discussed, and it is believed the apparatus will have applications in thin-layer phytoplankton research.

show abstract

Section: Introductionmentioning

confidence: 99%

Observation of nanosecond laser induced fluorescence of in vitro seawater phytoplankton

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Because triplet states have relatively long lifetimes, they can accumulate during the course of the pulse train. Quenching of fluorescence by singlet-triplet fusion has been observed recently by several groups of investigators (6,(12)(13)(14)(15)(16)(17)(18). …”

mentioning

confidence: 95%

Light collection and harvesting processes in bacterial photosynthesis investigated on a picosecond time scale

Campillo

Hyer

Monger

et al. 1977

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

View full text Add to dashboard Cite

Fluorescence lifetimes have been determined for four strains of Rhodopseudomonas sphaeroides. Chromatophore samples were excited with a single picosecond flash, and the fluorescence was detected with a streak camera. The decay times are 100 psec in strains 2.4.1 and Ga, and 300 psec in the carotenoidless strain R-26. These times are related to the transfer of energy from the light-harvesting antenna pigment molecules to the photochemical reaction center. In strain PM-8 dpl, which lacks reaction centers, the lifetime is 1.1 nsec. In addition, we have obtained curves relating the quantum yield of fluorescence to the photon density of the excitation pulse. These curves can be fit with a simple model that relates excitonic processes to properties of the photosynthetic unit and that qualitatively describes differences between the mutant strains. Picosecond laser techniques are now being widely applied in this field of biophysics, especially in the area of photosynthesis. Picosecond flash-photolysis techniques have identified transitions occurring in the primary photochemical reaction in photosynthetic bacteria (1, 2), and streak-camera measurement techniques have been used to measure rapid transfer of excitations between chlorophyll molecules in vivo (3-6). Other recent biophysical applications of picosecond or subnanosecond techniques include measurements on hemoglobin (7), visual pigments (8), and DNA (9-11).This paper is concerned with a determination by picosecond techniques of the kinetics with which the light-harvesting antenna pigment molecules of photosynthetic bacteria transfer energy to the photochemical reaction center. We have used two approaches to this problem. In the first approach, the sample is excited with a 20-psec pulse of low intensity and the fluorescence lifetime is measured. This time reflects the rate of depopulation of excited singlet states of bacteriochlorophyll in the antenna, mainly due to their capture by the reaction center. In the second approach, high-intensity pulses are used to generate nonlinear optical effects. High intensities produce a high density of excited states, leading to exciton annihilation processes, as Mauzerall (12) has demonstrated with nanosecond pulses and Campillo et al. (13) with picosecond pulses. Such processes have now been studied by several groups (6, 12-18). When two or more singlet excitations are simultaneously present in the photosynthetic unit (or within a certain diffusion radius), they can migrate into the vicinity of one another, and singlet-singlet annihilation can take place by the reactions Si +Si Sn + SO [1] Sn -"Si + heat [21 Eq. 1 represents a bimolecular fusion process in which a molecule in the first excited singlet state SI transfers its energy to a similarly excited neighboring molecule, promoting it to a higher singlet state S,. Because higher excited singlet states in large molecules such as bacteriochlorophyll almost always decay nonradiatively to the S1 state, as shown in Eq. 2, the net result is the loss of one excited singlet...

show abstract

“…In most commonly used four-wave-mixing techniques, such as pump-probe, three-pulse peak shift and photon echo, doubleexciton information is convoluted with single-exciton resonances, which complicates the analysis (15,16,(20)(21)(22)(23). The present technique (20,24), analogous to double-quantum coherence techniques in multidimensional NMR (25), has shown high sensitivity to coupling patterns and high spectral resolution in vibrational excitons (11,(26)(27)(28).…”

mentioning

confidence: 98%

“…In the native environment, under the intense flux of sunlight, photosynthetic complexes have multiple electronic excitations, the interactions of which cause dissipation of the excess energy (1,2,9,15,16). Biological complexes have developed various protective mechanisms for excess energy discharge to avoid overheating and damage (17,18).…”

mentioning

confidence: 99%

Double-quantum resonances and exciton-scattering in coherent 2D spectroscopy of photosynthetic complexes

Abramavičius

Voronine

Mukamel

2008

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

View full text Add to dashboard Cite

A simulation study demonstrates how the nonlinear optical response of the Fenna-Matthews-Olson photosynthetic light-harvesting complex may be explored by a sequence of laser pulses specifically designed to probe the correlated dynamics of double excitations. Cross peaks in the 2D correlation plots of the spectra reveal projections of the double-exciton wavefunctions onto a basis of direct products of single excitons. An alternative physical interpretation of these signals in terms of quasiparticle scattering is developed.exciton transport ͉ femtosecond spectroscopy ͉ photosynthesis ͉ light harvesting T he photosynthetic apparatus depends on light-harvesting complexes, which absorb photons and funnel their energy to reaction centers where it is converted and stored as chemical energy (1, 2). The Fenna-Matthews-Olson (FMO) complex is the prototype photosynthetic antenna (3, 4). The complex (Fig. 1) is a trimer of identical units, each containing seven chlorophyll a chromophores embedded in the protein matrix. The structure and properties of the complex have been studied extensively over the past decade (3-7).Electronically excited FMO complexes prepared by the absorption of a single photon are well understood, and their properties are described by the Frenkel exciton model (2,8,9). The elaborate exciton-relaxation pattern can be monitored by using multidimensional coherent optical spectroscopy (10-12): peak redistribution on the picosecond time scale reflects excited-state population relaxation (7), whereas femtosecond oscillations indicate electronic coherences (13). Excited-state lifetimes, intraband excitonrelaxation pathways (7,14), and long-lived electronic quantum coherences (13) have been reported, and the Hamiltonian parameters were refined to simulate these measurements.In the native environment, under the intense flux of sunlight, photosynthetic complexes have multiple electronic excitations, the interactions of which cause dissipation of the excess energy (1, 2, 9, 15, 16). Biological complexes have developed various protective mechanisms for excess energy discharge to avoid overheating and damage (17,18). Understanding the coherent many-exciton dynamics, which precedes the incoherent relaxation, is necessary for revealing the initial steps in excitation dynamics. Information about the two-exciton manifold is also important for the applications of the coherent control of excitedstate dynamics of photosynthetic complexes (19). Doubleexciton resonances are much more complicated and less studied than the single excitations. Exciton annihilation, which depends on incoherent multiexciton dynamical properties, often complicates the analysis of nonlinear optical measurements.In this article we present simulations of an impulsive thirdorder 2D coherent spectroscopic (2DCS) technique aimed at directly probing double-exciton features in an FMO complex. In most commonly used four-wave-mixing techniques, such as pump-probe, three-pulse peak shift and photon echo, doubleexciton information is convoluted with single...

show abstract

Picosecond exciton annihilation in photosynthetic systems

Cited by 102 publications

References 18 publications

Observation of nanosecond laser induced fluorescence of in vitro seawater phytoplankton

Observation of nanosecond laser induced fluorescence of in vitro seawater phytoplankton

Light collection and harvesting processes in bacterial photosynthesis investigated on a picosecond time scale

Double-quantum resonances and exciton-scattering in coherent 2D spectroscopy of photosynthetic complexes

Contact Info

Product

Resources

About