Please use this identifier to cite or link to this item:
|Title:||Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone||Authors:||Dias, Fernando B.
Monkman, Andrew P.
Burrows, Hugh D.
|Issue Date:||21-Feb-2006||Publisher:||American Chemical Society||Citation:||Macromolecules. 39:4 (2006) 1598-1606||Abstract:||The luminescence decay kinetics of polyfluorene copolymers containing fluorenone units randomly distributed along the polymer chain have been studied by steady-state and time-resolved fluorescence techniques in toluene solution. The typical green emission from polyfluorenes containing 9-fluorenone moieties is only observed if the 9-fluorenone group is covalently attached to the polymer. Small-angle neutron scattering (SANS) measurements indicate that, independent of the 9-fluorenone fraction, all the studied copolymers adopt an open wormlike conformation. This prevalent 1-dimensional arrangement confirms that the green emission observed with polyfluorenes is not the result of excimer formation in the typical sandwich-like conformation. Analysis of time-resolved fluorescence decays by the maximum entropy method (MEM) collected at the polyfluorene emission (415 nm) and by global analysis of decays collected at 415 and 580 nm (the 9-fluorenone defect emission wavelength) clearly indicates two different time regimes in the population of the fluorenone defect: one occurring in the time interval of 10 to 30 ps and a second one occurring in the time range from 70 to 200 ps. While the slower process shows a linear dependence with the 9-fluorenone fraction, compatible with a hopping migration process along the polymer chain, the faster process does not show such a dependence and instead suggests a short-range Dexter mechanism. These findings are in agreement with our previous work where the presence of a faster component was suggested.||URI:||http://hdl.handle.net/10316/10453||ISSN:||0024-9297||DOI:||10.1021/ma052505l||Rights:||openAccess|
|Appears in Collections:||FCTUC Química - Artigos em Revistas Internacionais|
Show full item record
Files in This Item:
|Fast and Slow Time Regimes of Fluorescence Quenching.pdf||195.35 kB||Adobe PDF||View/Open|
checked on May 29, 2020
WEB OF SCIENCETM
checked on Sep 2, 2021
checked on Sep 23, 2021
checked on Sep 23, 2021
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.