EXCITATION ENERGY TRANSFER IN THE CRYPTOPHYTES. FLUORESCENCE EXCITATION SPECTRA AND PICOSECOND TIME-RESOLVED EMISSION SPECTRA OF INTACT ALGAE AT 77 K

The absorption and luminescence of new boron-containing dyes in two-component films of Alq3 (matrix)-dye(impurity) (obtained by the method of thermal vacuum deposition) are studied. The comparison of the spectra of absorption, fluorescence, and fluorescence excitation of a dyes in one-component solutions and double-component films shows the existence of the effective electronic excitation energy transfer (EEET) from the matrix to dye molecules. Time-resolved spectra of two-component films also manifest strong EEET in these systems. For the estimation of the average exciton spreading length in Alq3 films, the diffusion model of the motion of singlet excitons is used. The diffusion coefficient is evaluated using time-resolved spectroscopy. The optimum concentrations of dyes in a light-emitting layer of OLED are evaluated based on experimental data and the used model of EEET.

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Photoassociation due to electron transfer. Exciplex formation in non-polar solvent

Australian Journal of Chemistry ◽

10.1071/ch9711797 ◽

1971 ◽

Vol 24 (9) ◽

pp. 1797 ◽

Cited By ~ 12

Author(s):

RJ McDonald ◽

BK Selinger

Keyword(s):

Polar Solvent ◽

Excitation Energy Transfer ◽

Acceptor Pair ◽

Excitation Spectra ◽

Fluorescence Excitation ◽

Exciplex Formation ◽

Reversible Dissociation ◽

Fluorescence Excitation Spectra ◽

Donor Acceptor ◽

Donor Acceptor Pair

Exciplexes may be formed by exciting either partner of a given electron donor-acceptor pair. As the formation of such exciplexes is reversible, dissociation may lead to excitation energy transfer. �� The temperature dependence of fluorescence excitation spectra has proved to be a powerful tool for exploring these systems.

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Structure of a cyanobacterial photosystem I surrounded by octadecameric IsiA antenna proteins

Communications Biology ◽

10.1038/s42003-020-0949-6 ◽

2020 ◽

Vol 3 (1) ◽

Cited By ~ 4

Author(s):

Fusamichi Akita ◽

Ryo Nagao ◽

Koji Kato ◽

Yoshiki Nakajima ◽

Makio Yokono ◽

...

Keyword(s):

Energy Transfer ◽

Excitation Energy ◽

Photosystem I ◽

Fluorescence Spectra ◽

Protein A ◽

Excitation Energy Transfer ◽

Electron Microscopic ◽

Time Resolved ◽

Closed Ring ◽

Membrane Spanning

AbstractIron-stress induced protein A (IsiA) is a chlorophyll-binding membrane-spanning protein in photosynthetic prokaryote cyanobacteria, and is associated with photosystem I (PSI) trimer cores, but its structural and functional significance in light harvesting remains unclear. Here we report a 2.7-Å resolution cryo-electron microscopic structure of a supercomplex between PSI core trimer and IsiA from a thermophilic cyanobacterium Thermosynechococcus vulcanus. The structure showed that 18 IsiA subunits form a closed ring surrounding a PSI trimer core. Detailed arrangement of pigments within the supercomplex, as well as molecular interactions between PSI and IsiA and among IsiAs, were resolved. Time-resolved fluorescence spectra of the PSI–IsiA supercomplex showed clear excitation-energy transfer from IsiA to PSI, strongly indicating that IsiA functions as an energy donor, but not an energy quencher, in the supercomplex. These structural and spectroscopic findings provide important insights into the excitation-energy-transfer and subunit assembly mechanisms in the PSI–IsiA supercomplex.

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