Photoluminescence mediation

Hiratani, T., Konishi, K., Surface cap-mediated host-guest chemistry of semiconductor CdS Intercalative cation accumulation around a phenyl-capped CdS cluster and its notable effects on the cluster photoluminescence. Angew. Chem., Int. Ed. 2004, 43, 5943-5946. 

Together with the Banin group, the authors of Refs [10-12] carried out optical spectroscopy investigations on some of the cluster molecules obtained ] 14-16]. These materials were treated as the molecular limit of the bulk semiconductor CdSe, and issues such as oscillator strength, steady-state and time-resolved photoluminescence and photoluminescence excitation were addressed. In addition, emission-mediating vibrational modes were detected, and photobleaching effects observed. 

We have previously shown that when PPV is self-assembled with specific electronically active polyanions such as poly(thiophene acetic acid) (PTAA) or sulfonated fiillerenes (S-C60 )(7), the photoluminescence of the PPV is essentially completely quenched by the polyanion. The mechanism of this quenching is believed to be due to a photoinduc electron transfer process taking place between the excited PPV and the adjacent electroactive polyanion molecules. The quenching process, in this case, is not associated with a Forster type energy transfer since in both cases, the required spectral overlap of a donor emission band with an acceptor absorption band is not fulfilled. In addition, photo-induced electron transfer processes have previously been confirmed in PPV/C60 systems and can be exploited to fabricate thin film photovoltaic devices (77). In order to mediate this electron transfer process, we have constructed multilayer heterostructures in which the PPV donor and the polyanion electron acceptor are separated from each other with electronically inert spacer layers of known thickness. In addition to allowing studies of the electron transfer process, such structures provide important insights into the thermal stability of the multilayer structure. The "spacers" used in this study were bilayers of SPS/PAH with an experimentally determined bilayer thickness of 30 +/-5 A. 

The excitation quantum yield ( ex) is the product of the efficiencies of (1) the chemical reaction, (2) the conversion of chemical potential into electronic excitation energy and in the case of sensitized chemiluminescence, and (3) the energy transfer. As a consequence, most chemiluminescent reactions have relatively low quantum yields compared to those of photoluminescence the exception being the enzymatically mediated bioluminescent processes. In spite of this low quantum efficiency, chemiluminescence remains an attractive option for chemical analysis. This stems from three factors (1) improved... 

Stewart MP, Buriak JM (2001) Exciton-mediated hydrosilylation on photoluminescent nanocrys-talline silicon. J Am Chem Soc 123 7821-7830... 

Takeda E, Nakamura T, Fujii M, Miura S, Hayashi S (2006) Surface plasmon polariton mediated photoluminescence from excitons in silicon nanocrystals. Appl Phys Lett 89(10) 101907 Tsybeskov L, Duttagupta SP, Fauchet PM (1995) Photoluminescence and electroluminescence in partially oxidized porous silicon. Solid State Commun 95(7) 429-433 Tsybeskov L, Duttagupta SP, Hirschman KD, Fauchet PM (1996) Stable and efficient electroluminescence from a porous silicon-based bipolar device. Appl Phys Lett 68(15) 2058-2060 Valenta J, Lalic N, Linnros J (2004) Electroluminescence of single silicon nanocrystals. Appl Phys Lett 84(9) 1459-1461... 

AUen MJ, Buriak JM (1999) Photoluminescence of porous silicon surfaces stabilized through Lewis acid mediated hydrosilylation. J Lumin 80 29-35 Anglin EJ, Cheng L, Freeman WR, Sailor MJ (2008) Porous silicon in drug delivery devices and materials. Adv Drug Deliv Rev 60 1266-1277... 

Buriak JM, Allen MJ (1998b) Photoluminescence of porous silicon surfaces stabilized through Lewis acid mediated hydrosilylation. J Luminesc 80 29-35... 

Lu C.H., Hong H.C., Jagannathan R. Sol-gel synthesis and photoluminescent properties of cerium-ion doped yttrium aluminium garnet powders. J. Mater. Chem. 2002 12 2525-2530 Marsh P.J., Silver J., Vecht A., Newport A. Cathodoluminescence studies ofyttrium silicate cerium phosphors synthesized by a sol-gel process. J. Lumin. 2002 97 229-236 Meyer F., Hempehnann R, Mathur S., Veith M. Microemulsion mediated sol-gel synthesis of nano-scaled MAI2O4 (M = Co, Ni, Cu) spinels from single-source heterobimetallic alkoxide precursors. J. Mater. Chem. 1999 9 1755-1763... 

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