ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
A time-correlated single photon counting technique, coupled with a red sensitive photomultiplier tube, was used to determine the singlet-state lifetimes and energy transfer mechanisms of Chl a⋅H2O, (Chl a⋅H2O)2, and (Chl a⋅2H2O)n. The use of low concentrations and low incident light fluxes permitted measurements in a regime where nonlinear quenching effects are absent. The lifetimes exhibit a pronounced dependence on aggregate size. The results are examined in terms of exciton interactions in the excited singlet state of the Chl a aggregate. It is shown that in the absence of exciton annihilation effects, the rate of singlet-state decay via radiative coupling and intersystem crossing of a Chl a aggregate containing n equivalent monomeric units is equal to n times that of monomeric Chl a.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.448500
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