Mendis Madu N, Mandal Himadri S, Waldeck David H
Department of Chemistry, University of Pittsburgh, 219 Parkman Street, Pittsburgh PA 15260, USA.
J Phys Chem C Nanomater Interfaces. 2013 Dec 5;117(48):25693-25703. doi: 10.1021/jp410000u.
This work reports on the observation of a delocalized surface plasmon resonance (DSPR) phenomenon in linear chains of square-shaped silver nanoparticles (NP) as a function of the chain length and the distance between the nanoparticles in the chain. Transmission spectra of the silver nanoparticle chains reveal the emergence of new, red-shifted extinction peaks that depend strongly on the spacing between the nanoparticles and the polarization of the exciting light with respect to the chain axis. As the spacing between the nanoparticles in the linear chain decreases and the number of nanoparticles in the linear chain increases, the strength of the new extinction features increase strongly. These changes can be described by a tight-binding model for the coupled chain, which indicates that the origin of the phenomenon is consistent with an increased coupling between the nanoparticles. FDTD calculations reveal that the electric field is strongly enhanced between the nanoparticles in the chain. The DSPR response is found to be much more sensitive to dielectric changes than the localized surface plasmon resonance (LSPR).
这项工作报道了在方形银纳米颗粒（NP）线性链中观察到的离域表面等离子体共振（DSPR）现象，该现象是链长以及链中纳米颗粒之间距离的函数。银纳米颗粒链的透射光谱揭示了新的、红移的消光峰的出现，这些峰强烈依赖于纳米颗粒之间的间距以及激发光相对于链轴的偏振。随着线性链中纳米颗粒之间的间距减小且线性链中纳米颗粒的数量增加，新消光特征的强度显著增强。这些变化可以用耦合链的紧束缚模型来描述，这表明该现象的起源与纳米颗粒之间耦合的增加一致。有限时域差分（FDTD）计算表明，链中纳米颗粒之间的电场得到了强烈增强。发现DSPR响应比局域表面等离子体共振（LSPR）对介电变化更为敏感。
