Preparation And Characterization Of Novel Nanostructured Materials

Surface Plasmon Polaritions(SPPs)are a vibrations mode generated by free electrons in a plasma excited by an external electric field and interacting with an electromagnetic field and collectively oscillating at the interface between the metal and the non-metal dielectric.Such electromagnetic waves can interact with luminescent excitons such as J-aggregates,dye molecules,photochromic molecules,quantum wells,and Quantum Dots(QD).When the vibrational frequencies of the two substances are the same,energy resonance will occur,and a new coupled hybrid state will be formed.An energy difference will be formed between the new hybrid states.This energy difference is called Rabi splitting.When the Rabi splitting energy satisfies the strong coupling criterion,this interaction is called strong coupling.Strong coupling is the foundation of quantum information technology and has gradually become a research hotspot in recent years.Strong coupling is caused by surface plasmon resonance.This resonance has a strong amplification effect on the excitation process of the molecule,which can effectively enhance the energy released when the free electrons undergo a transition of the energy level in the molecule,thus affecting Quantum efficiency,relaxation lifetime,and fluorescence emission direction of the process.Studies have shown that the structural changes of metal nanomaterials can have a great impact on the strong coupling resonance mode.By skillfully designing the nanomaterial structure,effective control of strong coupling can be achieved.In the study of strongly coupling's experimental materials,most of the choices for exciton materials are concentrated on J-aggregates or dye molecules.However,organic molecules are easily bleached and cannot withstand high light intensity.Quantum dots capable of producing tunable,highly efficient emission and absorption of engineered electron energy levels are relatively more stable in optical properties.Therefore,core-shell nanostructured materials composed of metal nanoparticles and quantum dots have gradually become a new choice in the field of strong coupling research.In this paper,a new core-shell nanostructured material-_silver nanoprism@SiO2@QD(Ag Nanoprism@SiO2@QD,abbreviated as AgNP@SiO2@QD)was synthesized from the mechanism of strong coupling.In the preparation of the nanostructured material,we first prepared a silver nanoprism with a side length of about 50 nm and a thickness of about 8 nm.The absorption spectrum peak is at 650 nm,and it interacts with the J-aggregates can produce a 270meV Rabi splitting.In order to control the distance between the quantum dots and the silver nanoprism and reduce the corrosion caused by the contact of the inner silver nanoprism with the outside air,we uniformly coat the surface of the silver nanoprism with a layer of SiO2.The SiO2 layer can be adjusted in thickness by controlling the dose of Tetraethylorthosilicate(TEOS)to meet the different distances of the coupling components in the strong coupling experiment.At present,the mainstream method of coating metal nanoparticles with SiO2 is still the Stober method.In the experiment,we found that when dimethylamine(Dimethylamine,hereinafter referred to as DMA)was used instead of ammonia to make TEOS hydrolysis catalyst,it could significantly inhibit the corrosion of metal nanoparticles and inhibit the growth of crystalline SiO2 spheres.Finally,the quantum dots are attached to the silicon dioxide layer by chemical bonds.In order to verify the optical properties of the AgNP@SiO2@QD nanocomposite structure,we analyzed it by FDTD simulation method.The results show that the nanostructured material can generate Rabi split with energy of 112 meV under the excitation of the light source,and it is found by calculation that it satisfies the strong coupling criterion.And with the increase of the number of outer quantum dots,the Rabi splitting strength is gradually increasing.