金纳米粒子对染料分子光学性质的影响

研究了金纳米粒子对染料罗丹明6G（R6G）和荧光素（FL）光学性质的影响。表面有柠檬酸根保护层的金纳米粒子吸附带正电荷的罗丹明6G后，其表面等离子体共振红移；但吸附带负电荷的荧光素后，其表面等离子体共振几乎不受影响，这可能与粒子之间的静电作用有关。罗丹明6G的表面增强拉曼光谱表明其平躺吸附在金纳米粒子表面，非辐射能量转移的发生和不利的吸附取向导致罗丹明6G荧光信号强度减弱，相反，荧光素由于与金纳米粒子表层柠檬酸根之间有静电排斥作用，产生了一段距离，使得荧光信号增强。

The Influence of Gold Nanoparticles on the Optical Properties of Dye Molecules

The influence of gold nanoparticles on the optical properties of dye molecules of Rhodamine 6G (R6G) and fluorescein (FL) has been studied. The adsorption of positively charged R6G on the surface of gold nanoparticles passivated with citrate resulted in a red-shift of the surface plasmon resonance (SPR) of the gold nanoparticles. Negatively charged FL, on the other hand, had slight influence on the SPR of the gold nanoparticles, likely due to the electrostatic repulsion between FL and citrates. The surface-enhanced Raman spectrum of R6G on the gold nanoparticles demonstrated that R6G adapted a parallel orientation relative to the surface of the gold nanoparticles. The nonradiative energy decay and unfavorable orientation of R6G to gold nanoparticles led to a decrease in the intensity of the emission of R6G. In contrary, the emission intensity of FL was substantially increased in the presence of the gold nanoparticles, due to the necessary space generated by the electrostatic repulsion between FL molecules and the citrate-passivated gold nanoparticles.