Preparation, Characterization And Application Of Zero-dimensional Nanophotoelectric Materials

In this thesis,the preparation methods,characterization and application of zerodimension nano-photoelectric material,especially germanium nanocrystals?Ge-ncs?and silver nanoparticles?Ag NPs?have been studied.Firstly,the microstructure of Ge-ncs has been studied by transmission electron microscopy?TEM?,which could be a theoretical basis to the preparation of a specific size of Ge-ncs.Then two kinds of yeast cells with different cell walls were successfully distinguished by surface enhanced Raman scattering?SERS?at single-cell level using Ag NPs as active substrates.Meanwhile,the cell secretions were detected,which could be beneficial to the study of rapid detection of drug-resistant bacteria.The thesis consists of four chapters.In chapter 1,The application of nanomaterials in the field of new energy and biomedical was reviewed,followed by the simple introduction of Ge-ncs and SERS theory.In chapter 2,A systematic TEM study of Ge-nc produced by ion implantation in SiO₂/Si systems shows that both the dimension and the size-dispersion of formed nanoclusters increase continuously with the concentration of Ge introduced into the samples.The biggest Ge-nc are produced in the sample region where the local concentration of Ge is the highest.Defining the minimum quantity of Ge needed to form nanocrystals with diameters varying from 1 to 10 nm.The quantity of implanted Ge participating into the Ge-nc nucleation was estimated between 60 and 40% in the studied samples.In chapter 3,Ag NPs were prepared by chemical reduction and used as SERS active substrates to do the research at single cell level.It turned out that,the reproducibility of Ag NPs which covered polyvinylpyrrolidone?PVP?as a surface-protecting agent is much better,and screening two different yeast cells clearly by SERS.In chapter 4,The origin of SERS signal is determined to come from Escherichia.Coli secretions and is the difference stress response between Streptococcus mutant and Escherichia.Coli discovered,which can be applied to bacteria identification.The phenomenon of Escherichia coli resistance based on stress response is explored to provide the date base of resistant bacteria rapid detection.