scholarly journals Picosecond Absorption Spectroscopy of Energy Transfer Processes in Polymethine Dyes

1990 ◽  
Vol 10 (3) ◽  
pp. 139-145 ◽  
Author(s):  
K. -H. Feller ◽  
R. Gadonas ◽  
V. Krasauskas
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Iron Complex ◽  
Polymethine Dyes ◽  
Acceptor Molecule ◽  
Time Resolved ◽  
Transfer Processes ◽  
Energy Donor ◽  
First Time ◽  
Polymethine Dye

Results are presented of time-resolved absorption investigations of energy transfer processes between a polymethine dye and an iron complex dye (dye E). For the first time the acceptor molecule transient absorption depletion generated by energy transfer from an excited donor was observed. The decay time of the acceptor deactivation (≈ 140 Ps) in the presence of the energy donor agrees very well with the S1-state lifetime of the energy donor.

Photoinduced electron and energy transfer processes in rotaxanes containing zinc porphyrin as pendant and [60]fullerene and ferrocene as axle ends

2005 ◽  
Vol 09 (10) ◽  
pp. 724-734 ◽  
Author(s):  
Mio Maes ◽  
Hisahiro Sasabe ◽  
Nobuhiro Kihara ◽  
Yasuyuki Araki ◽  
Yoshio Furusho ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Charge Separation ◽  
Transient Absorption ◽  
Recombination Rates ◽  
Time Resolved ◽  
Transient Absorption Spectra ◽  
Transfer Processes ◽  
Nonpolar Solvents ◽  
Electron Transfer Processes ◽  
Absorption Measurements

Photoinduced electron-transfer processes of a newly synthesized rotaxane containing porphyrinatozinc ( ZnP ), [60]fullerene ( C 60), and ferrocene ( Fc ) have been studied in terms of the time-resolved fluorescence and transient absorption measurements in polar and nonpolar solvents. In this rotaxane, ( ZnP ; C 60- Fc ) rotax , ZnP was chosen as a pendant of a crown-ether necklace, through which an axle with C 60 and Fc at both termini was penetrated. By the selective excitation of the ZnP moiety in a nonpolar solvent, energy transfer predominantly takes place to the C 60 moiety of ( ZnP ; C 60- Fc ) rotax . In polar solvents, charge-separation process takes place via the excited singlet state of the ZnP moiety in addition to the energy-transfer process. From the nanosecond transient absorption spectra, a clear absorption band of the C 60•− moiety was observed at 1000 nm as well as a broad absorption in the 600-800 nm region due to ZnP •+, suggesting the generation of ( ZnP •+; C 60•−- Fc ) rotax in the first step. Afterward, the hole-transferring process from ZnP •+ to Fc is thermodynamically possible, although this process is not fast because of its through-space process character. The final lifetimes of the C 60•− moiety were evaluated to be 290 and 370 ns in benzonitrile and DMF, respectively. The ratios of the charge-separation rates to charge-recombination rates were ca. 1000, indicating that ( ZnP ; C 60- Fc ) rotax affords an efficient photosynthetic model.

scholarly journals Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

2012 ◽  
Vol 3 ◽  
pp. 629-636 ◽  
Author(s):  
Gilad Gotesman ◽  
Rahamim Guliamov ◽  
Ron Naaman
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Horizontal Plane ◽  
Quartz Substrate ◽  
Vertical Direction ◽  
Time Resolved ◽  
Transfer Processes ◽  
Donor And Acceptor ◽  
Hybrid Assemblies ◽  
Time Resolved Photoluminescence

We studied the photoluminescence and time-resolved photoluminescence from self-assembled bilayers of donor and acceptor nanoparticles (NPs) adsorbed on a quartz substrate through organic linkers. Charge and energy transfer processes within the assemblies were investigated as a function of the length of the dithiolated linker (DT) between the donors and acceptors. We found an unusual linker-length-dependency in the emission of the donors. This dependency may be explained by charge and energy transfer processes in the vertical direction (from the donors to the acceptors) that depend strongly on charge transfer processes occurring in the horizontal plane (within the monolayer of the acceptor), namely, parallel to the substrate.

scholarly journals Investigations of the Energy Transfer in the Phycobilisome Antenna of Arthrospira platensis Using Femtosecond Spectroscopy

2020 ◽  
Vol 10 (11) ◽  
pp. 4045
Author(s):  
Alexandra Fălămaș ◽  
Sebastian A. Porav ◽  
Valer Tosa
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Single Photon ◽  
Global Analysis ◽  
Photon Counting ◽  
Excitation Energy Transfer ◽  
Arthrospira Platensis ◽  
Absorption Data ◽  
Time Resolved ◽  
Photocurrent Amplification

Understanding the energy transfer in phycobilisomes extracted from cyanobacteria can be used for building biomimetic hybrid systems for optimized solar energy collection and photocurrent amplification. In this paper, we applied time-resolved absorption and fluorescence spectroscopy to investigate the ultrafast dynamics in a hemidiscoidal phycobilisome obtained from Arthrospira platensis. We obtained the steady-state and time-resolved optical properties and identified the possible pathways of the excitation energy transfer in the phycobilisome and its components, phycocyanin and allophycocyanin. The transient absorption data were studied using global analysis and revealed the existence of ultrafast kinetics down to 850 fs in the phycobilisome. The fluorescence lifetimes in the nanosecond time-scale assigned to the final emitters in each sample were obtained from the time-correlated single photon counting fluorescence experiments.

Decoupling the artificial special pair to slow down the rate of singlet energy transfer

2012 ◽  
Vol 16 (05n06) ◽  
pp. 685-694 ◽  
Author(s):  
Pierre D. Harvey ◽  
Adam Langlois ◽  
Mikhail Filatov ◽  
Daniel Fortin ◽  
Kei Ohkubo ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Absorption Spectroscopy ◽  
Density Functional ◽  
Transient Absorption ◽  
Geometry Optimization ◽  
Transient Absorption Spectroscopy ◽  
Free Base ◽  
Functional Theory ◽  
Time Resolved ◽  
Slow Rise

Trimer 2, composed of a cofacial heterobismacrocycle, octamethyl-porphyrin zinc(II) and bisarylporphyrin zinc(II) held by an anthracenyl spacer, and a flanking acceptor, bisarylporphyrin free-base ( Ar = -3,5-(t Bu )2 C 6 H 3), has been studied by means of absorption spectroscopy, "steady state and time-resolved fluorescence" and fs transient absorption spectroscopy, and density functional theory (DFT) in order to assess the effect of decoupling the chromophores' low energy MOs on the rate of the singlet, S1, energy transfer, k ET , compared to a recently reported work on a heavily coupled trimeric system, Trimer 1, [biphenylenebis(n-nonyl)porphyrin zinc(II)]-bisarylporphyrin free-base ( Ar = -3,5-(t Bu )2 C 6 H 3). The position of the 0–0 peaks of the absorption and fluorescence spectra of Trimer 2 indicates that these porphyrin units are respectively energy donor 1, donor 2, and acceptor. The DFT computations confirm that the MOs of the cofacial donor 1-donor 2 dyad are decoupled, but significant MO coupling between donor 2 and acceptor 1 is still present despite the strong dihedral angle between their respective average planes (77.5°: geometry optimization by DFT). The fs transient absorption spectra exhibit a clear S1–Sn fingerprint of the bisarylporphyrin zinc(II) chromophore and the kinetic trace exhibits a slow rise time of 87 ps, due to a S1 donor 1 → donor 2 ET. The transient species donor 2 and acceptor decay respectively in the short (~1.5) ns and 6 ns time scale.

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