Department of Chemistry and The Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA, 02215, USA.
Nat Commun. 2018 Apr 23;9(1):1608. doi: 10.1038/s41467-018-04066-2.
Capacitive plasmon coupling between noble metal nanoparticles (NPs) is characterized by an increasing red-shift of the bonding dipolar plasmon mode (BDP) in the classical electromagnetic coupling regime. This model breaks down at short separations where plasmon-driven charge transfer induces a gap current between the NPs with a magnitude and separation dependence that can be modulated if molecules are present in the gap. Here, we use gap contained DNA as a scaffold for the growth of palladium (Pd) NPs in the gap between two gold NPs and investigate the effect of increasing Pd NP concentration on the BDP mode. Consistent with enhanced plasmon-driven charge transfer, the integration of discrete Pd NPs depolarizes the capacitive BDP mode over longer interparticle separations than is possible in only DNA-linked Au NPs. High Pd NP densities in the gap increases the gap conductance and induces the transition from capacitive to conductive coupling.
贵金属纳米粒子（NPs）之间的电容等离子体耦合的特点是，在经典电磁耦合区域中，键合偶极等离子体模式（BDP）的红移增加。在短距离下，该模型会失效，因为等离子体驱动的电荷转移会在 NPs 之间产生一个间隙电流，其大小和分离依赖于间隙中存在的分子，如果存在分子，则可以进行调制。在这里，我们使用包含间隙的 DNA 作为支架，在两个金 NPs 之间的间隙中生长钯（Pd）NPs，并研究了增加 Pd NP 浓度对 BDP 模式的影响。与增强的等离子体驱动电荷转移一致，离散 Pd NPs 的集成使电容 BDP 模式在比仅通过 DNA 连接的 Au NPs 更短的粒子间分离度上发生去极化。间隙中较高的 Pd NP 密度增加了间隙电导率，并诱导从电容耦合到导电耦合的转变。
