Single-molecule spectroscopy and femtosecond transient absorption studies on the excitation energy transfer process in ApcE(1–240) dimers

2015 ◽  
Vol 17 (20) ◽  
pp. 13387-13396 ◽  
Author(s):  
Saran Long ◽  
Meng Zhou ◽  
Kun Tang ◽  
Xiao-Li Zeng ◽  
Yingli Niu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Single Molecule ◽  
Transfer Process ◽  
Transient Absorption ◽  
Energy Transfer Process ◽  
Excitation Energy Transfer ◽  
Single Molecule Spectroscopy ◽  
Femtosecond Transient Absorption ◽  
Absorption Studies

The red-shifted absorption of ApcE dimers results from extending chromophore conformation, which does not depend on strong exction coupling.

Femtosecond Transient Absorption Studies of Energy Transfer within Chromophore-Labeled Dendrimers

2001 ◽  
Vol 105 (7) ◽  
pp. 1307-1312 ◽  
Author(s):  
Frederik V. R. Neuwahl ◽  
Roberto Righini ◽  
Alex Adronov ◽  
Patrick R. L. Malenfant ◽  
Jean M. J. Fréchet
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Femtosecond Transient Absorption ◽  
Absorption Studies

scholarly journals Excitation energy migration processes in various multi-porphyrin assemblies

2012 ◽  
Vol 370 (1972) ◽  
pp. 3802-3818 ◽  
Author(s):  
Jaesung Yang ◽  
Dongho Kim
Keyword(s):  
Excitation Energy ◽  
Single Molecule ◽  
Coherence Length ◽  
Radiative Decay ◽  
Transient Absorption ◽  
Excitation Energy Transfer ◽  
Building Blocks ◽  
Linear Arrays ◽  
Single Molecule Level ◽  
Structural Distortions

The electronic interactions and excitation energy transfer (EET) processes of a variety of multi-porphyrin arrays with linear, cyclic and box architectures have been explored. Directly meso – meso linked linear arrays ( Z N ) exhibit strong excitonic coupling with an exciton coherence length of approximately 6 porphyrin units, while fused linear arrays ( T N ) exhibit extensive π -conjugation over the whole array. The excitonic coherence length in directly linked cyclic porphyrin rings ( CZ N ) was determined to be approximately 2.7 porphyrin units by simultaneous analysis of fluorescence intensities and lifetimes at the single-molecule level. By performing transient absorption (TA) and TA anisotropy decay measurements, the EET rates in m -phenylene linked cyclic porphyrin wheels C12ZA and C24ZB were determined to be 4 and 36 ps −1 , respectively. With increasing the size of C N ZA , the EET efficiencies decrease owing to the structural distortions that produce considerable non-radiative decay pathways. Finally, the EET rates of self-assembled porphyrin boxes consisting of directly linked diporphyrins, B1A , B2A and B3A , are 48, 98 and 361 ps −1 , respectively. The EET rates of porphyrin boxes consisting of alkynylene-bridged diporphyrins, B2B and B4B , depend on the conformation of building blocks (planar or orthogonal) rather than the length of alkynylene linkers.

scholarly journals Beads on a Chain (BoC) Fluorescent Oligomeric Materials: Interactions of Conjugated Organic Cross-Linkers with Silsesquioxane Cages

2021 ◽  
Author(s):  
Shahrea Mahbub ◽  
Sukanya Saha ◽  
Ramakrishna Guda ◽  
Joseph Furgal
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Electronic Materials ◽  
Field Effect Transistors ◽  
Single Photon ◽  
Photophysical Properties ◽  
Excitation Energy Transfer ◽  
Transient Absorption Spectroscopy ◽  
Gravimetric Analysis

<div> <div> <div> <p>Organic electronic materials have advantages over inorganics in terms of versatility, cost and processability. Recent advancements in organic materials for light emitting diodes (OLED), field effect transistors (OFET), and photovoltaics have engendered extensive innovation potential on this field. In this research, we focus on synthesizing SQ (silsesquioxane) based oligomers cross- linked by di-bromo-aromatic linkers and explore how the cross-linker and oligomer length influence their photophysical properties. Bis-tri-alkoxy silyl (linker) model compounds were synthesized to compare non-cage photophysical properties with the oligomers. Several techniques such as UV/Vis, fluorescence, FTIR, thermal gravimetric analysis (TGA) have been used to characterize the systems. Time-resolved fluorescence and femtosecond transient absorption spectroscopy are used to understand the excited state dynamics of these materials. Studies are carried out to understand the differences between monomers and oligomers and potential energy transfer and charge transfer between the cages and cross-linking chromophores. Transient absorption showed lower energy absorption from the excited states, suggesting short range communication between moieties. Single photon counting studies have shown distinct lifetime differences between most linkers and cages showing possible excitation energy transfer through these materials. Transient absorption anisotropy measurements have shown signatures for excitation energy transfer between linker chromophores for oligomeric compounds. The silsesquioxane (SQ) backbone of the oligomers gives substantial thermal stability as well as solution processability, giving better flexibility for achieving energy transfer between linking chromophores. </p> </div> </div> </div>

scholarly journals Chlorophyll–carotenoid excitation energy transfer and charge transfer in Nannochloropsis oceanica for the regulation of photosynthesis

2019 ◽  
Vol 116 (9) ◽  
pp. 3385-3390 ◽  
Author(s):  
Soomin Park ◽  
Collin J. Steen ◽  
Dagmar Lyska ◽  
Alexandra L. Fischer ◽  
Benjamin Endelman ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Excitation Energy Transfer ◽  
Excited State Absorption ◽  
Thermal Dissipation ◽  
Live Cells ◽  
Nannochloropsis Oceanica

Nonphotochemical quenching (NPQ) is a proxy for photoprotective thermal dissipation processes that regulate photosynthetic light harvesting. The identification of NPQ mechanisms and their molecular or physiological triggering factors under in vivo conditions is a matter of controversy. Here, to investigate chlorophyll (Chl)–zeaxanthin (Zea) excitation energy transfer (EET) and charge transfer (CT) as possible NPQ mechanisms, we performed transient absorption (TA) spectroscopy on live cells of the microalga Nannochloropsis oceanica. We obtained evidence for the operation of both EET and CT quenching by observing spectral features associated with the Zea S1 and Zea●+ excited-state absorption (ESA) signals, respectively, after Chl excitation. Knockout mutants for genes encoding either violaxanthin de-epoxidase or LHCX1 proteins exhibited strongly inhibited NPQ capabilities and lacked detectable Zea S1 and Zea●+ ESA signals in vivo, which strongly suggests that the accumulation of Zea and active LHCX1 is essential for both EET and CT quenching in N. oceanica.

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