Aggregation-Induced Enhancement Effect of Gold Nanoparticles on Triplet Excited State

게시자: Hyung Min Kim, 2013. 12. 27. 오후 11:32

Remarkable optical properties are posed with gold nanoparticles (AuNPs) due to the excitation of localized surface plasmon resonances, which makes AuNPs affect strongly both the ground state and the excited state of adjacent organic molecules. Compared with the ground state, the effect of AuNPs on excited state of organic molecules is not always fully understood. Here, we performed transient UV–vis absorption experiments to monitor the triplet excited state formation of three cationic dyes and one anionic dye in the presence of two types of gold nanoparticles: the citrate-stabilized AuNPs and ATP-protected AuNPs. It is found that the three cationic dyes can cause efficient aggregation of citrate-stabilized AuNPs, leading to AuNPs aggregates with varied size, whereas the ATP-protected AuNPs can be sustained in the monodispersed state. By comparing the circumstances of aggregated AuNPs and monodispersed AuNPs, we demonstrate that the enhancement effect on triplet excited state formation results from the aggregation of gold nanoparticles and depends on the aggregation size. These findings reveal the aggregation induced plasmon field interaction of AuNPs with excited state population dynamics and may enable new applications of aggregated metal nanoparticles, where aggregates can serve as stronger plasmonic nanoantennas.

J. Phys. Chem. C, 2013, 117 (51), pp 27088–27095

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