F枚rster Resonance Energy Transfer and Laser Efficiency in Colloidal Suspensions of Dye-Doped Nanoparticles: Concentration Effects

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• 作者：Leire Gartzia-Rivero ; Luis Cerd谩n ; Jorge Ba帽uelos ; Eduardo Enciso ; 脥帽igo L贸pez Arbeloa ; 脕ngel Costela ; Inmaculada Garc铆a-Moreno
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：June 19, 2014
• 年：2014
• 卷：118
• 期：24
• 页码：13107-13117
• 全文大小：438K
• 年卷期：v.118,no.24(June 19, 2014)
• ISSN：1932-7455

文摘

The donor and acceptor concentration effects on F枚rster resonance energy transfer (FRET) and laser properties of polymer nanoparticles (NPs) highly doped with two dyes are comprehensively analyzed. Rhodamine 6G (Rh6G, donor) and Nile Blue (NB, acceptor) are incorporated into anionic methacrylic NPs 40 nm in size, in concentrations [Rh6G] = 1鈥? mM and [NB] = 0.5鈥?1 mM. The FRET efficiency is mostly influenced by the acceptor concentration due to the presence of more available energy traps and a reduction in the average donor/acceptor distances. We show that the presence of homo-FRET among donors may give rise to an enhancement on the net hetero-FRET efficiency mainly when the concentration of donors exceeds that of the acceptors. When the concentration of both dyes is raised beyond a given value, the FRET efficiency is reduced due to the influence of competing quenching processes. Carefully selected mixtures of Rh6G/NB allow achieving FRET efficiencies as high as 88% and efficient laser emission in which the excitation/pumping light has been fully transferred from Rh6G (575 nm) to NB (700 nm). Finally, it is shown that, although a higher FRET efficiency does not guarantee higher acceptor laser efficiencies, both are mostly affected by the acceptor concentration and the total amount of dye molecules inside the NPs. This study acquires special relevance since the use of NPs not only allows achieving FRET efficiencies much higher than those attainable in liquid solution (88% vs 57%) but also opens the door to the study of FRET dynamics at concentrations beyond the solubility limit in liquid solutions and without the undesirable effects of reabsorption/re-emission processes (at least for the Rh6G/NB pair).