Font Size: a A A

Preparation Of Silicon Nanowire Arrays And Silver Nanostructures And Its SERS Application

Posted on:2013-02-06Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y K WuFull Text:PDF
GTID:1111330371496643Subject:Optics
Abstract/Summary:PDF Full Text Request
Surface Enhanced Raman Spectroscopy (SERS) has attracted extensive attention since its discovery, and the upsurge of life science offers a passionate stage for SESR. SERS substrates are the precondition and key of SERS research, but the preparation of SERS substrates with high enhancement factor as well as outstanding uniformity and reproducibility is still a challenge. The main works are listed as follow:1, A brief introduction was given to the related theory of SERS, and the influence of the properties of nanoparticles, exciting laser and surrounding medium on the SERS activity were discussed; We track the advance of SERS substrates, and give a presentation to gold/silver nanoparticles, gold/silver coated silicon nanowires (SiNW) and several novel SERS substrates selectively. At last, we summarize the merit and demerit of SERS, and give an overview to the applications of SERS in the detection of cells, biomolecules and single molecule.2, Microwave heating method and ultraviolet irradiation method were employed to prepared silver colloids. The size and shape of silver colloids prepared by microwave heating method were heterogeneous, while the size and shape of silver colloids prepared by ultraviolet irradiation method were uniform relatively. Using rhodamine6G as probe molecule, SERS experiments revealed that, the reproducibility of silver colloids resolution substrates was good, but the enhancement ability was somewhat low; the enhancement ability of solid silver colloids on cover glass was perfect sometimes, but the uniformity and reproducibility was poor.3, Large-area uniform and vertical SiNW arrays were prepared by chemical wet etching. It was found that the length of SiNW arrays increased with the increase of etching time, but the relationship were not linear, the etching velocity increased first then decreased. By contrast, the etching velocity in the ultrasonic wave method are higher than that in temperature-controled method, and the aggregation effect of the SiNW arrays was also relieved in the ultrasonic wave method.4, SERS substrates with high enhancement activity and excellent uniformity were prepared through integrating silver colloids with SiNW arrays. Additionally, through immersion plating method, silver nanostructrues were also decorated onto SiNW arrays, the original structure of SiNW arrays was affected by the chemical reaction, and the silver nanostructures were not uniform along the axis of SiNWs. Moreover, millipore silicon arrays were also used as templates for silver nanostructures, and novel silicon-based silver nanostructures were obtained through immersion plating method, and the enhancement ability and uniformity of the novel SERS substrates were both good. Besides, the Finite Difference Time Domain (FDTD) simulations revealed that the optimal enhancement factor of two parallel SiNWs irradiated orthogonally was huge.5, The influence of temperature and laser irradiation on the morphology and SERS activity of gold/silver alloy films was probed in-situ with the combination of Atomic Force Microscopy (AFM) and Raman spectroscopy. The in-situ temperature-controled experiments revealed that gold/silver alloy nanoparticles began to coarsen at50℃, and the SERS activity decreased as the temperature increased. Besides, laser irradiation caused the coarsening of gold/silver alloy nanoparticles and the decrease of SERS activity.The as-prepared silicon-based silver nanostructures, using as SERS substrates, possess high enhancement factor as well as outstanding uniformity and reproducibility, and can be used for the preparation of on-chip SERS substrates.
Keywords/Search Tags:Surface Enhanced Raman Spectroscopy, Surface Plasmon Resonance, Ag Nanoparticles, SiNW Arrays, SERS Substrates
PDF Full Text Request
Related items