Mr. Patrick Lynch Profile

Patrick Lynch

at Technological Univ Dublin

SPIE Involvement:

Author

Publications (3)

This will count as one of your downloads.

You will have access to both the presentation and article (if available).

DOWNLOAD NOW

This content is available for download via your institution's subscription. To access this item, please sign in to your personal account.

Email or Username Forgot your username?

Password Forgot your password?

Show

Keep me signed in

No SPIE account? Create an account

Proceedings Article | 3 June 2005 Paper

Relationships for electron-vibrational coupling in conjugated Pi organic systems

L. O'Neill, P. Lynch, M. McNamara, H. Byrne

Proceedings Volume 5826, (2005) https://doi.org/10.1117/12.603380

KEYWORDS: Raman spectroscopy, Polymers, Molecules, Luminescence, Spectroscopy, Absorption, Systems modeling, Absorption spectroscopy, Infrared spectroscopy, Data modeling

Read Abstract +

A series of π conjugated systems were studied by absorption, photoluminescence and vibrational spectroscopy. As is common for these systems, a linear relationship between the positioning of the absorption and photoluminescence maxima plotted against inverse conjugation length is observed. The relationships are in good agreement with the simple particle in a box method, one of the earliest descriptions of the properties of one-dimensional organic molecules. In addition to the electronic transition energies, it was observed that the Stokes shift also exhibited a well-defined relationship with increasing conjugation length, implying a correlation between the electron-vibrational coupling and chain length. This correlation is further examined using Raman spectroscopy, whereby the integrated Raman scattering is seen to behave superlinearly with chain length. There is a clear indication that the vibrational activity and thus nonradiative decay processes are controllable through molecular structure. The correlations between the Stokes energies and the vibrational structure are also observed in a selection of PPV based polymers and a clear trend of increasing luminescence efficiency with decreasing vibrational activity and Stokes shift is observable. The implications of such structure property relationships in terms of materials design are discussed.

Proceedings Article | 3 June 2005 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

Read Abstract +

Photoluminescence intensity PL measurements were taken for a range of PmPV concentrations, in which HiPco single walled carbon nanotubes (SWNTs) at 100%, 10%, 1%, 0.1%, 0.01% and 0% mass fractions were added. The PL intensity of the composite was shown to decrease for all mass fractions, relative to the polymer up to 1.56x10^-3g/l of PmPV, above which there is an initial increase in the composite emission yield with respect to the polymer. This increase is associated with an interaction within the composite, which results in a decrease in polymer aggregate formation, which has been shown to quench intensity yields. Within the concentration range studied 5.9x10^-8g/l to 2g/l the photoluminescence intensity yield for each system is highly non linear. Previously the ratio of the maximum PL intensity of the composite, which includes both, bound and unbound polymer chains, and the maximum PL intensity of the polymer, which includes only unbound polymer chains was plotted as a function of polymer concentration. From this the authors calculated the amount of free polymer within each composite and derived a model, which showed that as the polymer concentration is lowered the bundles break up until isolated SWNTs are stable at low concentrations. In particular for their 100% mass fraction polymer/HiPco SWNT it was shown that individual nanotubes are stable in solutions ~3x10^-5kg/m³. Here we utilize this approach and results indicate that as the mass fraction of nanotubes in reduced, individual nanotubes are stable at higher polymer concentrations. In particular for our 100% mass fraction results indicate that below ~1.5x10^-4g/l individual nanotubes are stable. This result indicates that the choice of polymer and or solvent has a significant effect on the debundling and aggregation within these systems.

Proceedings Article | 3 June 2005 Paper

Structural property relationships in conjugated polymers

P. Lynch, L. O'Neill, J. Whelan, M. McNamara, H. Byrne

Proceedings Volume 5826, (2005) https://doi.org/10.1117/12.598779

KEYWORDS: Polymers, Luminescence, Ultraviolet radiation, Spectroscopy, Electrons, Solids, Nitrogen, Absorbance, Crystals, Absorption

Read Abstract +

The synthesis of a series of PPV derivative polymers by the Wittig-Horner reaction is described. The structure of each polymer is varied and the effects of these variations on the optical properties is explored. The effects of alkyloxy side chains is observed between the PPV derivatives Poly(-p-phenylvinylene-co-2,5-bis-octyloxy phenylvinylene.) PPV-OPV and Poly (para-2,5-bis-(n-octyloxy)-phenylvinylene) POPV. The phenyl units of the soluble PPV derivative POPV are replaced by alternate naphthyl units in the polymer Poly(2,5-bis(n-octyloxy)-1,4-phenylene vinylene-1,5-bis(n-octyloxy)-2,6-naphthylene vinylene) POPN-ONV and then fully by naphthyl units in Poly(2,6-bis-(n-octyloxy)-1,5-NaphthyleneVinylene) PONV. The addition of alkyloxy sidechains served to red shift the fluorescence emission as expected. The systematic conversion of phenyl to naphthyl units blue shifted the emission considerably while reducing the Stokes shift. There is evidence to suggest some localization of the pi electrons over the aromatic units of the polymer backbone. PONV is shown to have greater stability towards photo-oxidation then either POPV or PPV-OPV.

My Library

You currently do not have any folders to save your paper to! Create a new folder below.

Folder Name

Folder Description

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks. You are receiving this notice because your organization may not have SPIE eBooks access.*

*Shibboleth/Open Athens users─please sign in to access your institution's subscriptions.

To obtain this item, you may purchase the complete book in print or electronic format on SPIE.org.

ORGANIZATIONAL
Sign in with credentials provided by your organization.

Organizational Username

Organizational Password

Show/Hide Password

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members:

Non-members: ADD TO CART

Keywords/Phrases

Search In:

Publication Years