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Gallagher, Shane A.
Preferred name
Gallagher, Shane A.
Official Name
Gallagher, Shane A.
Research Output
Now showing 1 - 3 of 3
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Publication
Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin
2012-09-24, Keane, Páraic M., Gallagher, Shane A., Magno, LuÃs M., Leising, Miriam J., Clark, Ian P., Greetham, Gregory M., Towrie, Michael, Gun'ko, Yurii, Kelly, John M., Quinn, Susan J.
The photophysical properties of 2.3 nm thioglycolic acid (TGA) coated CdTe quantum dots (QDs) prepared by a reflux method have been studied in the presence of cationic meso-tetrakis(4-N-methylpyridyl) zinc porphyrin (ZnTMPyP4). Addition of the CdTe QDs to the porphyrin in H2O
results in a marked red-shift and hypochromism in the porphyrin
absorption spectrum, indicative of a non-covalent binding interaction
with the QD surface. Only low equivalents of the quantum dot were
required for complete quenching of the porphyrin fluorescence revealing
that one quantum dot may quench more than one porphyrin. Similarly
addition of porphyrin to the quantum dot provided evidence for very
efficient quenching of the CdTe photoluminescence, suggesting the
formation of CdTe'porphyrin aggregates. Definitive evidence for such
aggregates was gathered using small angle X-ray spectroscopy (SAXS).
Ultrafast transient absorption data are consistent with very rapid
photoinduced electron transfer (1.3 ps) and the resultant formation of a
long-lived porphyrin species.
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Synthesis and spectroscopic studies of chiral CdSe quantum dots
2010-08, Gallagher, Shane A., Moloney, MÃcheál P., Wojdyla, Michal, Quinn, Susan J., Kelly, John M., Gun'ko, Yurii K.
Using microwave irradiation, water soluble, optically active, penicillamine (Pen) capped CdSe nanocrystals with broad spectral distribution (430-780 nm) of photoluminescence have
been produced and studied by a range of instrumental techniques including absorption, circular dichroism and both steady state and time resolved photoluminescence spectroscopy. The photoluminescence of these nanocrystals is attributed to emission from surface defect states. The decay of the excited state in the nanosecond region, which can be analysed as a triple exponential, depends strongly on the emission wavelength
selected, but only weakly on the excitation wavelength.
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Publication
Efficient Quenching of TGA-Capped CdTe Quantum Dot Emission by a Surface-Coordinated Europium(III) Cyclen Complex
2013-03-25, Gallagher, Shane A., Comby, Steve, Wojdyla, Michal, Quinn, Susan J., et al.
Extremely efficient quenching of the excited state of aqueous CdTe quantum dots (QDs) by photoinduced electron transfer to a europium cyclen complex is facilitated by surface coordination to the thioglycolic acid capping ligand. The quenching dynamics are elucidated using steady-state emission and picosecond transient absorption.