氯金酸-罗丹明S缔合纳米微粒体系的共振散射增强与荧光猝灭研究

在0．2mol/L HCl介质中，罗丹明S(RDS)分别在520nm和550nm处有一个吸收峰和荧光峰。当有Au(Ⅲ）存在时，Au（Ⅲ）与Cl^-形成AuCl4^-，AuCl^-与RDS^ 借助于静电引力形成疏水性的AuCl4-RDS缔合物分子。AuCl4-RDS分子间存在较强的分子间作用力和疏水作用力而生成(AuCl4-RDS)。缔合纳米微粒，粒径为45nm。在360nm产生瑞利散射峰，在600nm产生共振散射峰。由于纳米微粒形成后，只有裹露在(AuCl4-RDS)n纳米微粒界面的RDS荧光分子才能吸收激发光子跃迁到激发态，进而返回基态产生荧光。而体相的RDS荧光分子无法与激发光作用产生荧光，即受激RDS分子数大为降低，故550nm荧光峰和520nm吸收峰的降低。当缔合纳米微粒体系加入乙醇后，体系的红紫色和共振散射峰消失，吸收峰和荧光峰恢复，由于乙醇致使(AuCl4-RDS)。纳米微粒分解为AuCl4-RDS分子。结果表明：红紫色(AuCl4-RDS)n纳米粒子的形成是其共振散射增强、荧光猝灭和产生共振散射峰的根本原因。

Enhanced Resonance Scattering and Fluorescence Quenching Behavior of (AuCl4-Rhodamine S)n Association Nanoparticle System

There are a maximum absorption peak at 520 nm and a fluorescence peak at 550 nm for rodamine S (RDS) in the medium of 0.2 mol/L HCl. The AuCl - 4 and RDS + combine into hydrophobic AuCl 4-RDS association molecule by means of static gravitation. There are stronger Van de Waals forces and hydrophobic forces among AuCl 4-RDS molecules. So it forms (AuCl 4-RDS)n association nanoparticle in red-violet that exhibit a Rayleigh scattering peaks at 360 nm and a resonance scattering peaks at 600 nm. The diameter of the nanoparticle is about 45 nm. The fluorescence quenching at 550 nm and the absorption peak decreasing at 520 nm are owing to that the RDS molecule in the body of the nanoparticle may not be excited by incidence photons, and it does not emit fluorescence. The (AuCl 4-RDS) n nanoparticle can be decomposed into AuCl 4-RDS association molecule by alcohol. So that, the resonance scattering peaks and the red-violet disappear. And the absorption peak at 520 nm and fluorescence peak at 550 nm/510 nm appear again when alcohols are added into the association nanoparticle system. The results demonstrate that the formation of (AuCl 4-RDS) n association nanoparticle in red-violet is results for its enhanced Rayleigh scattering and fluorescence quenching and a resonance scattering peaks at 600 nm.