The Investigation On Deep UV Surface Plasma Properties Of Metal Nanoparticles With Its Application

The surface plasmon resonance (SPR) is the collective oscillation of free-electron gas if metal nanoparticals exposure to external electromagnetic (EM) field, it was discovered in 1902 by American physicist R. W. Wood in the optical experimen. Due to the various application of SPR, such as surface enhanced Raman scattering (SERS)[8], photoelectric detector signal enhancement, etc, more and more research has focused on SPR. Although SPR is very common in metals, to date, most of the researchers only focus on typical nobel metals, such as silver (Ag) and gold (Au) who’s SPR peaks is located in visible area or near infrared area (NIR). Those noble metals’light frequency in the deep ultraviolet are larger than the plasma frequency of the metal, most of the light spread to the metal were absorbed, so they are not suitable for excitation in deep ultraviolet (DUV) region. However, other metals, especially those peaks in deep ultraviolet area rarely observed in the experiment, most of the researchers only focus on Al. There are many other metals plasma resonance in DUV region are still not observed in the experiment, mainly because of the preparation method. In addition, DUV-SPR will opens much more applications, such as fluorescent observation of biological specimens without labeling dyes, and laser ablation with high energy photons, because of their higher energy than that of visible light. So, find a feasible method for preparation of metal nanoparticles with DUV-SPR is of great significance.(1) Most of the metals are very active in nanoscale, so common methods are difficult to prepare high pure and dispersive metal nanoparticles efficiently and rapidly. We find that laser ablation in liquid (LAL) where a solid target is ablated to generate primary products in gas or plasma state have many advantages. The liquid laser ablation have rapid, universal and simple properties, we only need a high purity metal target material as a raw material and then we can get high purity metal nanoparticles in the liquid phase environment simply, rapidly in low-temperature. Moreover, the liquid organic medium thermal decomposition by heating, forming a carbon layer in the surface of metal particles to prevent the oxidation of the metal nanoparticles and the carbon shell of the metal nanoparticles will have certain influence to the SPR response of the metal core. However, the LAL needs adjustment a series of parameters, such as laser energy, ablation time and the solution, to prepare stable and uniform morphology metal nanoparticles. In this paper, we employ LAL method to synthesis a series metal nanoparticals with carbon shell successfully with 1064 nm laser energy ablate 3 min in the methanol (MeOH) and ethanol (EtOH) mixed solution (mixing proportion of one to one).These series metal nanoparticals includes eight kinds of metal and they are chemically stable with carbon shell. Then, we studied the deep ultraviolet surface plasma resonance and we demonstrated the enhancement of carbon fluorescence with the existence of metal. By the research, we find that, this method which synthesised in rapidly environment can be used for deep ultraviolet plasma material platform by researching their SPR property. It is of great significance in preparation of metal nanoparticles with DUV-SPR and expanding the SPR applications.(2) Through PS spheres,this thesis use vacuum evaporation to prepare a series Al array of nano thin film.And by adjusting the size of PS spheres, we realize to adjusting the morphology of the Al nano film.And so we can optimize the SPR peaks of the Al nano films.We also compound the Al nano films with diamond film to prepare a diamond UV detector. Finaly we find that SPR has a gain to diamond UV detectors.And this reseach will also extend the future of the SPR area.