Studies On The Single Particle Light Scattering Spectroanalytical Chemistry Of Zinc Oxide Dielectric Resonators

Dielectric nanoresonators?DNRs?have been widely used in the fields of enhanced spectroscopy,biosensing,etc.owing to their unique optical resonance properties.Similar to the localized surface plasmon resonance?LSPR?properties of noble metal nanoparticles,the optical resonance properties of DNRs are influenced by the material,shape,size,microenvironment of the medium and coupling between nanoparticles,which have tunable light scattering properties.However,at present,the research on the optical properties of DNRs mainly focused on the nanostructures such as Si and Ge,while the research on semiconductor oxides such as TiO₂,ZnO and Cu₂O,which have the advantages of simple synthesis method and lower optical loss,is not sufficient.In addition,the application of the light scattering properties of DNRs in the analysis and detection mainly focused on the regular array structures,and there are few reports at the single particle level.Therefore,this thesis takes zinc oxide dielectric resonators?ZnO DRs?as the research object,and aims at the shortcomings of the current DNRs in light scattering analysis research,and carried out the following research contents:1.Dark-Field light scattering imaging of ZnO DRs.Considering that the light scattering properties of dielectric materials are similar to the LSPR properties of noble metal nanoparticles,that is,the shape and size of particles are one of the important factors that affect their light scattering properties.Therefore,we synthesized ZnO DRs with different morphologies by adjusting the ratio of reactants.Combining dark-field microscope?DFM?imaging and scanning electron microscope?SEM?co-localization techniques,the DFM imaging characteristics of ZnO DRs with different morphologies were studied.It was found that they have an edge effect phenomenon similar to large-scale plasmonic nanoparticles,and the structure-dependent of scattered light color.On the basis,the effect of the medium microenvironment and substrate on the scattered light of ZnO DRs was investigated.The results show that although the ZnO DRS has different morphology,the scattered light intensity of ZnO DRS decreases obviously with the increase of the solvent refractive index?RI?,which is in good agreement with the Mie scattering formula.On the other hand,through a comparative study,it was found that the response sensitivities of ZnO DRs with different morphologies to solvents'RI had the following rules:the complex structure is higher than the simple structure,that is,X-type>Y-type>flakes>rods.This research laid a certain foundation for further expanding the application of ZnO materials in the field of light scattering analysis.2.Optical sensing performance of rod-shaped ZnO DRs at single particle level.In order to explore the light scattering properties and the light scattering analysis and sensing properties of ZnO dielectric resonators,so that it can be used preferably in the field of light scattering analysis.Herein,for the first time,we used zinc oxide microrods?ZnOMRs?as DFM imaging probes,the light scattering properties of ZnOMRs and their optical sensing performance at single particle level were systematically explored.It was found that the scattered light color of ZnOMRs is structure-dependent and polarization-dependent.On the other hand,it was found that the scattering light response of ZnOMRS to solvents'RI is just opposite to that of plasmonic noble metal nanoparticles,the scattered light intensity of ZnOMRs decreased sharply with the increase of solvents'RI,and the scattered light color gradually changed from yellow to yellow-green,especially when illuminated by transverse electric?TE?polarized light,showing polarization-dependent RI sensitivity properties.The unique light scattering characteristics of Zn OMRs and the polarization-dependent RI sensitivity characteristics provide more possibilities for the development of new single particle light scattering imaging analysis methods.3.In-situ and real-time dark-field light scattering imaging of Zn O@Au single particle growth.The composite nanostructure not only has the properties of a single component,but also may have synergistic properties or new properties,so it has attracted widespread attention and is also one of the research directions of composite nanospectral probes and composite nanomaterials.Especially the metal-semiconductor composite structure has been widely used in photocatalysis,solar cells etc.Based on this,we used ZnOMRs as DFM imaging probes,the light scattering signal of ZnOMRs as the output signal,using the properties of ZnO photogenerated electrons to photoreduction Au³⁺to gold nanoparticles and deposited on its surface,and the growth of a single ZnO@Au hybrid particle was observed in-situ and real-time,so as to explore the influence of particle element composition and morphology changes that may be involved in this growth process on its light scattering properties.It was found that the scattered light of ZnO@Au was blue-shifted and then red-shifted,and the scattered light intensity was decreases.This research enriches the research contents of ZnO optical properties,provides new ideas for monitoring the growth process of metal-semiconductor hybrid particles,and lays a certain foundation for the development of composite spectroscopy probes.In summary,this thesis takes ZnO DRs as the research object,and discusses the light scattering properties related to the elemental composition,shape,size,and medium microenvironment of ZnO DRs with the help of single particle light scattering analysis technology.Based on this,using ZnOMRs as DFM imaging probes,the optical sensing performance at single particle level was explored,and the growth process of single ZnO@Au hybrid particles was observed in-situ and real-time.It provides a certain experimental basis for the study of the optical properties of ZnO,expands the application range of ZnO in the field of light scattering analysis,and also expands the selection range of DFM imaging probes.