Synthesis and spectroscopic studies of composite gold nanorods with a double-shell structure composed of spacer and cyanine dye J-aggregate layers.
Synthesis and spectroscopic studies of composite gold nanorods with a double-shell structure composed of spacer and cyanine dye J-aggregate layers.
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DOI：
10.1021/la901431r
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发表时间：
2009-08
期刊：
影响因子：
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通讯作者：
Akihito Yoshida;Naoko Uchida;N. Kometani
中科院分区：
文献类型：
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作者：
Akihito Yoshida;Naoko Uchida;N. Kometani
合成了由Au-NR(核)、间隔层(内层)和J-聚集体(JA)层(外层)组成的复合金纳米棒(Au-NRS)，考察了局域表面等离子体与JA分子激子耦合的杂化体系的光谱性质。由N，N，N-三甲基(11-硫代十一烷基)氯化铵组成的间隔层在几种菁染料的JA壳的形成中起着重要的作用。当Au核的等离子体能量接近JA壳层的激子能量时，复合材料NRS的吸收光谱在J带附近有一个明显的凹陷，而当两个能量相差很大时，则出现一个正常的J带峰值。通过改变Au-NR的长径比来调制等离子体能量，观察到由浸润型吸收逐渐转变为峰型吸收。此外，通过在TMA和JA层之间插入聚电解质的多层壳层，制备了具有更厚间隔层的复合NRS。随着间隔层厚度的增加，它们呈现出由倾斜型到峰型的谱线形状变化。这些观测结果被用激子-等离子体激子耦合的强度来解释，激子-等离子体耦合强度对复合NRs的构型以及等离子体和激子能量之间的相对差异很敏感。
The composite gold nanorods (Au NRs) having a double-shell structure composed of Au NR (core), spacer layer (inner shell), and J-aggregate (JA) layer (outer shell) have been synthesized to examine the spectroscopic properties of the hybrid system in which the localized surface plasmon is coupled with the molecular exciton of JA. The spacer layer consisting of N,N,N-trimethyl(11-mercaptoundecyl)ammonium chloride plays a significant role in the formation of JA shell for several kinds of cyanine dyes. The absorption spectra of composite NRs are characterized by a distinct dip near the J-band when the plasmon energy of Au core is close to the exciton energy of JA shell, whereas a normal J-band peak appears when two energies are widely different from each other. The gradual change from the dip type to peak type absorption was observed when the plasmon energy was modulated by varying the aspect ratio of Au NR. Furthermore, composite NRs with thicker spacer layers have been fabricated by inserting the multilayer shell of polyelectrolytes between TMA and JA layers. They exhibited an alteration of the spectral line shape from the dip type to peak type with increase in the thickness of spacer layer. These observations have been interpreted in terms of the strength of the exciton-plasmon coupling, which is sensitive to the configuration of composite NRs as well as the relative difference between plasmon and exciton energies.