Mr. Garreth F. Farrell Profile

Garreth F. Farrell

at Technological Univ Dublin

SPIE Involvement:

Author

Publications (8)

Proceedings Article | 3 June 2005 Paper

Paper

Fluorescence concentration studies of HiPco SWNTs and semi-conjugated polymers

S. Keogh, T. Hedderman, E. Gregan, G. Farrell, P. Lynch, G. Chambers, F. Lyng, H. Byrne

Proceedings Volume 5826, (2005) https://doi.org/10.1117/12.605060

KEYWORDS: Polymers, Composites, Single walled carbon nanotubes, Luminescence, Carbon nanotubes, Fluorescence spectroscopy, Spectroscopy, Raman spectroscopy, Absorption, Molecules

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Proceedings Article | 3 June 2005 Paper

Paper

Electroabsorption studies of structurally modified fullerene thin films

G. Farrell, G. Chambers, H. Byrne

Proceedings Volume 5826, (2005) https://doi.org/10.1117/12.598747

KEYWORDS: Annealing, Absorption, Molecules, Fullerenes, Thin films, Crystals, Solid state physics, Spectroscopy, Data modeling, Temperature metrology

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Proceedings Article | 2 June 2005 Paper

Paper

Interaction of single walled carbon nanotubes with starch-based systems

A. Casey, G. Farrell, M. McNamara, H. Byrne, G. Chambers

Proceedings Volume 5824, (2005) https://doi.org/10.1117/12.604329

KEYWORDS: Polymers, Absorbance, Absorption, Single walled carbon nanotubes, Carbon nanotubes, Spectroscopy, Raman spectroscopy, Composites, Bromine, Iodine

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Proceedings Article | 27 August 2003 Paper

Paper

Excited state properties of C₆₀ revisited: a Raman study

Gordon Chambers, Siobhan Phelan, Garrett Farrell, Alan Dalton, Hugh Byrne

Proceedings Volume 4876, (2003) https://doi.org/10.1117/12.463668

KEYWORDS: Raman spectroscopy, Solids, Temperature metrology, Solid state physics, Crystals, Absorption, Thin films, Molecules, Nonlinear crystals, Photopolymerization

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Proceedings Article | 27 August 2003 Paper

Paper

Electronic transfer studies of fullerene/polymer hybrids

Garrett Farrell, Gordon Chambers, Alan Dalton, Hugh Byrne

Proceedings Volume 4876, (2003) https://doi.org/10.1117/12.463932

KEYWORDS: Absorption, Luminescence, Molecules, Polymers, Absorbance, Molecular energy transfer, Energy transfer, Spectroscopy, Carbon nanotubes, Photons

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Proceedings Article | 27 August 2003 Paper

Paper

Physical interactions between HiPco SWNTs and semiconjugated polymers

Sinead Keogh, A. Maguire, Theresa Hedderman, Elizabeth Gregan, Garrett Farrell, Alan Dalton, Brendan McCarthy, Gordon Chambers, Hugh Byrne

Proceedings Volume 4876, (2003) https://doi.org/10.1117/12.463665

KEYWORDS: Single walled carbon nanotubes, Polymers, Composites, Raman spectroscopy, Carbon nanotubes, Laser energy, Carbon, Absorption, Statistical analysis, Carbon monoxide

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Proceedings Article | 27 August 2003 Paper

Paper

Spectroscopic analysis of the intermolecular interactions of gamma cyclodextrin and carbon nanotubes

Gordon Chambers, Clodagh Carroll, Garrett Farrell, Alan Dalton, Martin Cadek, Mary McNamara, E. Cummins, Marc in het Panhuis, Hugh Byrne

Proceedings Volume 4876, (2003) https://doi.org/10.1117/12.463667

KEYWORDS: Single walled carbon nanotubes, Raman spectroscopy, Carbon nanotubes, Absorption, Spectroscopy, Time division multiplexing, Transmission electron microscopy, Crystals, Microscopy, Organic materials

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Proceedings Article | 27 August 2003 Paper

Paper

In-situ Raman spectroscopy of electrically generated species in fullerene thin films

Siobhan Phelan, Barry O'Connell, Garrett Farrell, Gordon Chambers, Hugh Byrne

Proceedings Volume 4876, (2003) https://doi.org/10.1117/12.463647

KEYWORDS: Raman spectroscopy, Crystals, Thin films, Fullerenes, Polymers, Electrodes, Temperature metrology, Electroluminescence, Aluminum, Solid state electronics

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Organic materials have, in recent decades, been shown to be insulators, semiconductors, or even metallic when doped and the prospect of cheap, easily fabricated devices has attracted much interest. Primitive devices have been demonstrated and yet potentially competitive performance has been limited to polymer light emitting diodes. The recent report that lattice expanded C₆₀ single crystals can be made superconducting, with a transition temperature of 117K, by the injection of charge via a FET type geometry has once again highlighted the potential of C₆₀ in the development of molecular electronic devices. In light of the aforementioned report it is essential that a true understanding of the inter- and intramolecular processes in terms of their contribution to the electronic transport be obtained. In this study the current voltage characteristics of C₆₀ thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behavior and a sharp increase in the device conductivity was observed at relatively low voltages (~2V), at both room and low temperatures (20K). At room temperature the system is seen to collapse, and in situ Raman measurements indicate a solid state reduction of the fullerene thin film to form a polymeric state. The high conductivity state was seen to be stable at elevated voltages and low temperatures. This state is seen to be reversible with the application of high voltages. At these high voltages the C₆₀ film was seen to sporadically emit white light at randomly localized points analogous to the much documented electroluminescence in single crystals. Moreover the evidence suggests that this highly conducting species maybe similar in nature to a high intensity optically excited species. It is further speculated that the species recently reported in the superconducting lattice expanded C₆₀ single crystals may also be analogous to the highly conducting species observed here.

Showing 5 of 8 publications

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