Two-photon Induced Luminescence Properties Of Noble Metal Nanoparticles Array

Due to the unique surface Plasmon (SP) and nonlinear optical properties, the noblemetal nanomaterials have widespread application prospect in nanophotonic devices, opticalsensor and bioimaging. The optical properties of noble metal nanoparticles are sensitive tothe particle size, its shape, interparticle spacing and dielectric environment. So we canmodulate SP through vary those conditions,thus can achieve different functions ofnanophotonic devices. In this dissertation, optical properties of2D periodic noble metalnanoparticles array were researched, by using UV-visible absorption spectroscopy tomeasure the effect annealing treatment, particle size and interparticle spacing on theabsorption, and measuring the fluorescence spectrum by the self-build optical platform.Themain content is as follows:(1) Combined Nanosphere Lithography with pulsed laser deposition technique, noblemetal (Au, Ag) nanoparticles periodical array with different sizes have been fabricated onquartz and the adjustable interparticle spacing nanopaticles periodical array on the flexiblepolydimethylsiloxane (PDMS) substrate. From scanning electron microscopy (SEM) and theatomic force probe (AFM) image, the surface morphology and the thickness of nanospheremask and periodical array of metal triangular-shaped nanoprisms can be obsevered.(2) By measuring UV-visible absorption spectroscopy from300nm to900nm, thestrong absorption band in the visible range caused by surface plasma resonance of noblemetal particles can be found,for Ag array430nm and Au array580nm respectively.Furthermore, after the annealing treatment, there is a blue shift of the absorption peaks of theAu nanoparticles, and the absorption peak become sharper and stronger.(3) By research the effects of interparticle spacing of nanoparticles on the SPR peak, wefound that with the decrease of interparticle spacing, the SPR peak shift to the red.Furthermore, theoretical calculation based on the finite difference time domain (FDTD)method was performed and the calculated results are in good agreement with experimental results. Meanwhile, we found the surface plasma field enhancement in the array structurewas compared with single particle and the particles couple by FDTD.（4）The photoluminescence of the Au nanoparticles array induced by the800nmfemtosecond laser is study systematically. By analysis the luminescence spectrum inducedby femtosecond laser with different power, we found the photoluminescence of Aunanoparticles mainly was single photon absorption induced when the power was low.However, two-photon absorption predominance when the power increased. By researchingthe Au nanoparticles array with different size (70nm and191nm), we found that the surfaceplasma field enhancement would affect the photoluminescence properties and theenhancement in two-photon luminescence was more obvious than in single photonluminescence.