Infrared Fluorescence Studies Of State-Selected Energy Transfer And Isotopic Chemistry

1976 ◽  
Author(s):  
Stephen R. Leone
2019 ◽  
Vol 66 (8) ◽  
pp. 879-885 ◽  
Author(s):  
Guangbo Xie ◽  
Haibang Zhang ◽  
Zijun Zhang ◽  
Juntong Liu ◽  
Jingjing Zhang ◽  
...  

1998 ◽  
Vol 543 ◽  
Author(s):  
Stephen F. Swallen ◽  
Raoul Kopelman ◽  
Jeffrey S. Moore

AbstractThe photophysics of exciton localization and energy transfer are examined in two unique classes of phenylacetylene dendrimers. One set of supermolecules is observed to efficiently and rapidly funnel absorbed radiation toward the molecular locus, while a slight change in molecular structure creates an effective “anti-funnel”, greatly reducing the efficiency of energy trapping. Lifetime-based and steady state fluorescence studies are used to determine the rates of intramolecular energy transfer and to glean information on molecular geometry and intermolecular interactions in two solvents.


Author(s):  
M. RAVIKUMAR ◽  
R. P. PANDIAN ◽  
T. K. CHANDRASHEKAR

The singlet and triplet excited state properties of two diporphyrins, H 2- H and Zn - H , are described. Steady state fluorescence studies indicate that the emission of the H 2- H diporphyrin is dependent on the excitation wavelength and is dominated by the emission of the individual constituent monomers at their respective excitation. Time-resolved studies show two lifetimes ascribable to the normal and thiaporphyrin subunits. However, the emission of the Zn - H diporphyrin is dominated by the thiaporphyrin subunit irrespective of the wavelength of excitation, suggesting an energy transfer from the Zn porphyrin subunit to the thiaporphyrin subunit. Lifetime measurements in toluene show two lifetimes due to open and folded conformations, while in DMF an additional component due to axial ligation is observed. The efficiency of energy transfer is moderately higher in DMF (72%) than in toluene (68%). Triplet ESR studies on the H 2- H dimer reveal a localized triplet with ZFS parameters and ESP pattern the same as for the individual monomers. On the other hand, triplet ESR of the Zn - H diporphyrin reveals triplet characteristics of the thiaporphyrin subunit, indicating an energy transfer in the triplet state.


Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1916
Author(s):  
Kamil Wiwatowski ◽  
Paweł Podlas ◽  
Magdalena Twardowska ◽  
Sebastian Maćkowski

Fluorescence microscopy and spectroscopy were applied for studying the optical properties of a hybrid nanostructure, in which we combine plasmon-induced metal enhanced fluorescence with energy transfer to epitaxial graphene. Covering the layer of silver islands with a monolayer graphene, while turning on the efficient energy transfer from emitters, only moderately affects the enhancement of fluorescence attributed to the plasmon resonance in metallic nanostructures—as evidenced by the analysis of fluorescence decays. The results show that it is feasible to combine the properties of graphene with metal-enhanced fluorescence. The importance of the layer thickness of the emitters is also pointed out.


1967 ◽  
Vol 155 (2) ◽  
pp. 296-308 ◽  
Author(s):  
Richard C. Powell ◽  
B. DiBartolo ◽  
B. Birang ◽  
C. S. Naiman

Author(s):  
STACY L. SPRINGS ◽  
ANDREI ANDRIEVSKY ◽  
VLADINÍR KRÁL ◽  
JONATHAN L. SESSLER

The synthesis of a new terephthalate-strapped porphyrin is described. This porphyrin, prepared in the form of the free base and corresponding zinc(II) complex, was designed to act as the photo-donor portion of a novel, non-covalent artificial light-harvesting complex, the other, acceptor component of which is comprised of a covalently linked sapphyrin dimer. UV-vis and 1 H NMR spectroscopic analyses were used to establish that strong complexes are formed between the porphyrin terephthalate and sapphyrin dimer components (affinity constants on the order of 105 M−1 in dichloromethane). In these complexes the dicarboxylate portion of the strapped porphyrin is sandwiched between two sapphyrins of an individual dimer. Steady state fluorescence studies of the resulting ensembles support the conclusion that, upon photoexcitation of the porphyrin subunit, energy transfer from the porphyrin to the sapphyrin dimer occurs efficiently. This intra-ensemble, anion-chelation-based energy transfer can be inhibited by the addition of fluoride anion.


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