Observation of coupling modes of surface plasmon resonance and local plasmon resonence and their applications to sensors

金胶体悬浮液的红色是由于金纳米颗粒中的自由电子在波长为520 nm的入射电场下发生共振振荡而引起的，这种共振称为表面等离子体共振，有时也称为局域等离子体共振。当金纳米颗粒靠近金属基底时，由于基底中诱导的镜像偶极，除了偶极之外，还在颗粒中激发出多极子，例如四极子。这导致谐振波长向更长波长移动。在研究中，研究了局域等离子体共振中的衬底效应。在实验中，将其上沉积有25 nm金膜的载玻片用作金属基底。通过沉积在金涂覆的玻璃基底上的氨基乙烷（AET）的自组装单层将金纳米颗粒固定到基底上。沉积的金纳米颗粒的直径小于100 nm。从测量的波长获得的共振波长 ...更多信息 将金纳米粒子的离子谱与其理论值进行了比较。从这些比较中发现，AET单层的厚度为0.3- 0.4nm。还观察到了粒子-粒子系统中的耦合模式。对于这一观察，一种新的技术，用于制造金纳米粒子多层膜，使用逐层沉积方法。聚（乙烯亚胺）和聚（乙烯基硫酸酯）被用作阳离子聚合物和阴离子聚合物和金纳米粒子夹在这些膜之间。在金纳米粒子的多层膜制造与这种技术是等于两个聚合物层的总和的厚度。随着粒径的增大，共振波长向长波方向移动。当这种纳米多层膜浸入乙醇-水混合物中时，共振波长随着水浓度的增加而向短波长移动。这是由金颗粒之间的聚合物膜的溶胀引起的。通过这些工作，证实了可以以亚纳米分辨率测量颗粒和颗粒的颗粒与基底之间的差距。少

The red color of gold colloid suspension is caused by the resonant oscillation of the free electrons in the gold nanoparticles with the incident electric field at 〜520 nm wavelength, The resonance is called surface plasmon resonance or sometimes local plasmon resonance. When the gold nanoparticle approach to a metal substrate, multipoles, such as a quadruple, are excited in the particle besides a dipole, due to the image dipole induced in the substrate. This causes a shift of the resonance wavelength toward longer wavelength. In research this substrate effect in the local plasmon resonance was investigated. In experiments slide glass on which a 25-nm gold film was deposited was used for a metal substrate. Gold nanoparticles were immobilized onto the substrate by a self-assembled monolayer of aminoethanethiol (AET) deposited onto a gold coated glass substrate. The diameter of the gold nanoparticles deposited were less than 100 nm. Resonance wavelengths obtained from the measured absorpt … More ion spectra of the gold nanoparticles were compared with its theoretical values. From these comparison it was found that the thickness of the AET monolayer is 0.3-0.4 nm. The coupling modes in particle-particle systems were also observed. For this observation a new technique for fabricating gold nanoparticle multilayers using a layer-by-layer deposition method. Poly (ethyleneimine) and poly (vinylsulfate) were used as a cationic polymer and an anionic polymer and gold nanoparticles were sandwiched between these films. In the gold nanoparticle multilayers fabricated with this technique is equal to the thickness of the sum of both polymer layers. The resonance wavelength shifted toward longer wavelength were observed as the particle size increased. When this nanoparticle multilayers were immersed into ethanol-water mixtures, the resonance wavelength shifted toward shorter wavelength as the water concentration increased. This is caused by the swelling of the polymer films between the gold particles. Through these works, it was confirmed that the gap between particle and substrate of particle and particle can be measured with subnanometer resolution. Less