Study On Resonance Fluorescence Enhancement Of Gold And Silver Nanoparticles

Gold and silver nanoparticles have become the object of many basic technology researches in recent years because of their particle size,shape,and unique optical and electrical properties.The surface plasmon resonance generated by the regular movement of the free electrons inside the gold and silver nanoparticles under the external electromagnetic field of a certain frequency can greatly enhance the electromagnetic field around the particles.Fluorescence spectroscopy technology is widely used in daily life because of its high sensitivity and diverse methods.However,in actual operation,the high sensitivity of fluorescence technology cannot meet all the requirements of measurement,and surface-enhanced fluorescence technology emerges at the historic moment.Gold and silver nanoparticles can greatly enhance the local electromagnetic field on the particle surface due to their special surface plasmon resonance,and change the free space environmental conditions of the fluorophores adsorbed on the particle surface and surrounding fluorophores,thereby enhancing the fluorescence intensity of fluorescent molecules..Surface enhanced fluorescence is an effect that can only occur in a certain space.The coating of the silica shell can not only adjust the relative distance between the fluorescent molecules and the gold and silver nanoparticles,but also avoid the quenching of the fluorescence.Greatly improve the dispersibility and stability of metal particles.In this paper,silica-coated gold and silver nanoparticles with different coating thicknesses were prepared,and the fluorescence of gold and silver nanoparticles with different coating thicknesses on Rhodamine B,Fluorescein,and Quinine sulfate were studied intensity action mechanism and action law.The main work is as follows:1.Gold nanorods,gold nanospheres,and silver nanoparticles were prepared by the seed-mediated growth method;gold and silver nanoparticles with different SiO₂ coating thicknesses were prepared by the St(?)ber method.The results showed that with the increase in the amount of TEOS,the gold and silver nanoparticles The larger the thickness of the SiO₂ core-shell covered by silver nanoparticles,the red shift distance of the surface plasmon resonance absorption peaks of gold and silver nanoparticles gradually increases.When the amount of TEOS is too large,TEOS aggregation will occur.2.By changing the amount of gold and silver nanoparticles coated with SiO₂,the volume with the largest fluorescence enhancement intensity for Rhodamine B and Fluorescein was explored,and the effect of the SiO₂ coating thickness of gold and silver nanoparticles on Rhodamine B and Rhodamine B and Fluorescein was investigated.The fluorescence effect of Fluorescein shows that gold and silver nanoparticles with different SiO₂ coating thicknesses have different fluorescence enhancement effects on Rhodamine B and Fluorescein aqueous solutions.3.The fluorescence enhancement effect is most obvious when the coating thickness of gold nanorods SiO₂ is 25 nm,the fluorescence intensity of Rhodamine B is increased by 1.4 times,and the fluorescence intensity of Fluorescein is increased by 2.3 times;when the thickness of SiO₂ coated with gold nanospheres is 23 nm The fluorescence enhancement effect is the most obvious when the fluorescence intensity of Rhodamine B is increased by 2.3 times,and the fluorescence intensity of Fluorescein is increased by1.66 times;when the coating thickness of silver nanoparticles SiO₂ is 27 nm,the fluorescence enhancement effect is the most obvious,and the fluorescence intensity of Rhodamine B It is increased by 1.6 times,and the fluorescence intensity of Fluorescein is increased by 3.3 times.Through comparison,it can be seen that silver nanoparticles with a coating thickness of 27 nm have the strongest fluorescence enhancement effect on fluorescent molecules,with a maximum enhancement factor of 3.3 times.4.By changing the amount of silver nanoparticles coated with SiO₂,the effect on the fluorescence intensity of Quinine sulfate was explored.The results showed that as the coating thickness of SiO₂ increased,the fluorescence intensity of Quinine sulfate was not significantly enhanced effect.