Theory of Singlet—Triplet Exciton Fusion

Rahman, Talat S.; Knox, Robert

doi:10.1002/pssb.2220580233

Cited by 50 publications

(11 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The long-lived quenchers observed both at room temperature and at 100°K could thus be triplet states of either chlorophyll a or carotenoids. Rahman and Knox [20] have shown that quenching of chlorophyll a singlets by chlorophyll a triplet excitons is feasible, thus indicating that this hypothesis is valid. Furthermore, the CL 60 nsec rise time in the fluorescence quantum yield following a brief actinic flash observed by Mauzerall [21] could also be related to the decay of triplets which were generated by the actinic flash.…”

Section: Resultsmentioning

confidence: 90%

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

Breton¹,

Geacintov²

1976

FEBS Letters

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 90%

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

Breton¹,

Geacintov²

1976

FEBS Letters

View full text Add to dashboard Cite

“…The population of triplet exci tons will increase from pulse to pulse until a steady-state concentration is estab lished. Drawing on recent estimates fo r the singlet-triplet fu sion rate fo r ChI in vivo (97), it was suggested (18) that it is plausible to expect singlets to be annihilated by triplet excitons in times of about 60 psec. This value is close to many of the fl uorescence lifetimes obtained with multiple pulse excitation described above.…”

Section: Picosecond Measurementsmentioning

confidence: 99%

Picosecond Flash Photolysis in Biology and Biophysics

Holten¹,

Windsor²

1978

Annu. Rev. Biophys. Bioeng.

View full text Add to dashboard Cite

Three years ago one of us was asked by a funding agency to dust off his crystal ball and assess the fu ture importance of picosecond studies to chemistry. After a careful "objective" review of what had been accomplished up to then, and trying hard not to appear self-serving, he boldly concluded that a modest increase in the level of fu nding for picosecond instrumental developments appeared to be justified. In the light of what has occurred since then, this recommendation can only be considered cowardly. Almost all application of picosecond techniques in biology and biophysics has taken place in the past 2 or 3 years. Valuable new insights have been gained and in some areas, notably photosynthesis, striking ad vances in understanding have been made. Why? What special magic do picosecond techniques hold for biology? To answer this question we must trace its roots back to chemistry. The vast majority of chemical and biochemical reactions are composed of many elementary steps. The primary steps, which involve energy migration, bond breakage, molecular rearrangements, and charge transfer, all occur in the time range fr om about 10-14 to 10-8 sec. The "slowness" of an overall reaction is usually determined by other considerations, such as steric fa ctors and diffusion of reactants to the site of reaction. Picosecond spectroscopy enables us for the fi rst time to take a look at these primary steps.In this review we fo cus on the new insights that picosecond studies have provided in several important areas of biology. The area that has received the greatest emphasis to date is photosynthesis, which undoubtedly is appropriate, since we are all dependent upon photosynthesis both for our origin and for our continued survival. Picosecond fluorescence studies in both plants and bacteria show that excitation energy migrates fr om the antenna or light-harvesting system to the . reaction center in times that range fr om 10 psec to about I nsec, depending upon 189

show abstract

“…The branching ratio k', corresponding to the smaller value off respective Y~, can easily be estimated. With no charge carriers present and without a magnetic field, the value of Y s is given by2° (18) where kl is the rate constant for the formation of the triplet pairs. From this, we calculate k' according to FIG.…”

Section: Substitution Of Nt(t) Of Eq (1) and Ns(t) Of Eq (7) Yieldsmentioning

confidence: 99%

Exciton–charge carrier interactions in the electroluminescence of crystalline anthracene

Wittmer¹,

Zschokke‐Gränacher²

1975

The Journal of Chemical Physics

View full text Add to dashboard Cite

The interactions of triplet excitons with trapped charge carriers are studied in anthracene single crystals. The triplet excitons are generated by the recombination of charge carriers through double injection. The lifetime of the triplet excitons is studied from the decay of the phosphorescence intensity in a transient measurement. The interaction rate constant for the trapped charge carriers is of the same order of magnitude as previous published data measured with single injection of electrons. It is further shown that the rate constant varies with different conditions of crystal growth. The simultaneous investigation of double injection delayed fluorescence reveals also a strong quenching of the delayed fluorescence from the excited singlet state by trapped charge carriers. Magnetic field measurements show that this quenching is partly due to an increased dissociation of the triplet pair state through the presence of charge carriers. The possibility of enhanced spin relaxation of the triplets in the pair state is also discussed.

show abstract

Theory of Singlet—Triplet Exciton Fusion

Cited by 50 publications

References 17 publications

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

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

Picosecond Flash Photolysis in Biology and Biophysics

Exciton–charge carrier interactions in the electroluminescence of crystalline anthracene

Contact Info

Product

Resources

About