Quenching of fluorescence of chlorophyll in vivo by long‐lived excited states

Breton, Jacques; Geacintov, Nicholas E.

doi:10.1016/0014-5793(76)80659-x

Cited by 31 publications

(7 citation statements)

References 13 publications

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“…On the other hand, a noticeable time delay can be observed in the PS I emission at 734 nm. This indicates that F730* functions mainly as an excitation acceptor in PS I. Invariability of rf within the long-wavelength band of PS I supports the conclusion about the mobile character of excitons in this pigment system [4].…”

Section: Methodssupporting

confidence: 69%

Low‐temperature fluorescence decay and energy transfer in photosynthetic units

Avarmaa

Kochubey²,

Tamkivi

1979

FEBS Letters

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Section: Methodssupporting

confidence: 69%

Low‐temperature fluorescence decay and energy transfer in photosynthetic units

Avarmaa

Kochubey²,

Tamkivi

1979

FEBS Letters

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“…When a single picosecond laser pulse is used for excitation of the fluorescence, singlet-singlet exciton annihilation is dominant. However, when a pulse sequence or microsecond duration excitation pulses are employed, annihilation of singlet excitons by triplet excitons is important (1)(2)(3). Experimentally, exciton annihilation manifests itself by a decrease in the lifetime of the fluorescence (4) and by a decrease in the integrated quantum yield of fluorescence, 4, as the intensity I of the excitation is increased (5)(6)(7).…”

Section: Introductionmentioning

confidence: 99%

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

Paillotin¹,

Swenberg²,

Breton³

et al. 1979

Biophysical Journal

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173

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A Pauli master equation is formulated and solved to describe the fluorescence quantum yield, phi, and the fluorescence temporal decay curves. F(t), obtained in picosecond laser excitation experiments of photosynthetic systems. It is assumed that the lowering of phi with increasing pulse intensity is due to bimolecular singlet exciton annihilation processes which compete with the monomolecular exciton decay processes; Poisson statistics are taken into account. Calculated curves of phi as a function of the number of photon hits per domain are compared with experimental data, and it is concluded that these domains contain at least two to four connected photosynthetic units (depending on the temperature), where each photosynthetic unit is assumed to contain approximately 300 pigment molecules. It is shown that under conditions of high excitation intensities, the fluorescence decays approximately according to the (time)1/2 law.

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“…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: 99%

“…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)(13)(14)(15)(16)(17)(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.…”

mentioning

confidence: 99%

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.

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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...

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Quenching of fluorescence of chlorophyll in vivo by long‐lived excited states

Cited by 31 publications

References 13 publications

Low‐temperature fluorescence decay and energy transfer in photosynthetic units

Low‐temperature fluorescence decay and energy transfer in photosynthetic units

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

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

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