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Triplet-State and Singlet Oxygen Formation in Fluorene-Based Alternating Copoly...
Fonseca, S. M.; Pina, J.; Arnaut, L. G.; Melo, J. Seixas de; Burrows, H. D.; Chattopadhyay, N.; Alcácer, L.; Charas, A.; Morgado, J.; Monkman, A. P.Data are reported on the triplet states of a series of fluorene-based A-alt-B type alternating copolymers based on pulse radiolysis-energy transfer and flash photolysis experiments. From the pulse radiolysis experiments, spectra are given for eight copolymers involving phenylene, thiophene, benzothiadiazole, and oligothienylenevinylene groups. Quantum yields for triplet-state formation (ΦT) have been obtained b...
Photophysics of an Indigo Derivative (Keto and Leuco Structures) with Singular ...
Melo, J. Seixas de; Rondão, R.; Burrows, H. D.; Melo, M. J.; Navaratnam, S.; Edge, R.; Voss, G.Spectral and photophysical properties of the indigo derivative Cibalackrot in keto and reduced (leuco) forms were studied by absorption spectra, fluorescence and pulse radiolysis and compared with the structurally similar indigo. With the keto form of this dye, fluorescence (phiF = 0.76) and intersystem crossing (phiT = 0.11) are dominant, whereas with indigo, efficient internal conversion (phiIC = 0.99) is obs...
On the triplet state of poly(N-vinylcarbazole)
Pina, J.; Seixas de Melo, J.; Burrows, H. D.; Monkman, A. P.; Navaratnam, S.Triplet state properties including transient triplet absorption spectrum, intersystem crossing yields in solution at room temperature and phosphorescence spectra, quantum yields and lifetimes at low temperature as well as singlet oxygen yields were obtained for poly(N-vinylcarbazole) (PVK) in 2-methyl-tetrahydrofuran (2-MeTHF), cyclohexane or benzene. The results allow the determination of the energy value for ...
Hole formation and transfer in poly[9,9-di(ethylhexyl)fluorene] and an amine en...
Burrows, H. D.; Seixas de Melo, J.; Forster, M.; Güntner, R.; Scherf, U.; Monkman, A. P.; Navaratnam, S.Pulse radiolysis has been used to study the positively charged state of isolated chains of poly[9,9-di(ethylhexyl)fluorene] in chloroform solution. This is found to have an absorption maximum at 560 nm and a weaker band around 420 nm. Intermolecular electron transfer is observed from the aromatic amine tri(p-tolylamine) to this species. With the corresponding polyfluorene derivative end-capped by an arylamine, ...
Triplet state dynamics on isolated conjugated polymer chains
Burrows, H. D.; Seixas de Melo, J.; Serpa, C.; Arnaut, L. G.; Miguel, M. da G.; Monkman, A. P.; Hamblett, I.; Navaratnam, S.http://www.sciencedirect.com/science/article/B6TFM-46MD9J0-5/1/ad58ae25c92bd62f507ea5a6a04f467d
Transient absorption spectra of triplet states and charge carriers of conjugate...
Burrows, H. D.; Miguel, M. da G.; Monkman, A. P.; Hamblett, I.; Navaratnam, S.The use of pulse radiolysis to study transient species in conjugated polymers in solutions is discussed, with particular reference to poly(2-methoxy-5-(2'-ethylhexoxy)-p-phenylenevinylene) (MEH-PPV). The excited triplet state is specifically generated by energy transfer on radiolysis of benzene solutions in the presence of suitable sensitisers, and its spectrum is reported. The presence of vibronic structure su...
Triplet state spectroscopy of conjugated polymers studied by pulse radiolysis
Monkman, A. P.; Burrows, H. D.; Miguel, M. da G.; Hamblett, I.; Navaratnam, S.Using the technique of pulse radiolysis we have elucidated the energies and kinetics of triplet states in soluble luminescent conjugated polymers. Using poly(2-methoxy,5-(2'-ethyl-hexoxy)-p-phenylenevinylene) MEH-PPV as an example we explain this technique and show how it can be used to study the triplet states in conjugated polymers. Triplet energy transfer is used to determine 11Ag-13Bu energy gaps and the ki...
The triplet state of the ladder-type methyl-poly(p-phenylene) as seen by pulse ...
Monkman, A. P.; Burrows, H. D.; Hamblett, I.; Navaratnam, S.; Scherf, U.; Schmitt, C.The lowest triplet state of a ladder poly(p-phenylene) (MeLPPP) has been produced by sensitised energy transfer following pulse radiolysis of benzene solution, and absorbs at 1.34 eV with a lifetime [greater-or-equal, slanted]170 [mu]s. An S0-T1 energy separation of 2.15 ± 0.07 eV was determined, in excellent agreement with recent phosphorescence measurements, confirming the validity of the technique for the de...
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