Research On Key Techniques Of Tip-enhanced Raman Spectroscopy System

Tip-enhanced Raman spectroscopy(TERS),as an important part of nanometer new material analysis,has rich application scenarios and great research potential.It has the advantages of surface enhanced Raman spectroscopy(SERS)and near-field optics.The shape information depends on the performance of SPM control system,the spectral information resolution breaks through the optical diffraction limit,and the detection sensitivity is high.In order to carry out further experiments and Research on TERS,this paper aims to design and build a complete set of tip enhanced Raman spectrum detection system.In this paper,micro Raman spectroscopy and tuning fork AFM are used to optimize the structure of the system,the incident light field and the metal probe to improve the performance of the system.Finally,on this basis,the spectral detection of nanomaterials was studied.First of all,through the study of the enhancement mechanism of TERS technology,it is clear that the key factors of the system include the surface material of the tip,the shape and size of the tip,the incident light field,the selection of the substrate and so on,and according to this,the design and construction of TERS system are carried out.The whole system is divided into micro Raman detection unit and tuning fork AFM control unit,and each unit module is designed and built.In particular,in order to solve the most difficult three-point precise alignment problem of tip sample focus in TERS system,the differential confocal module is used with tuning fork AFM feedback control.Finally,the TERS system is built,and each module precisely cooperates with the stable work.Secondly,the most critical part of the metal probe in TERS system is studied,and a new type of metal probe suitable for the study of TERS is designed and prepared.Through the analysis of enhancement mechanism and FDTD simulation,a kind of tungsten wire probe with inner arc silicon dioxide gold particles double-layer coating was designed.By adjusting the key parameters of the electrochemical corrosion probe device developed by the laboratory,the inner arc tungsten probe was prepared.On this basis,the silicon dioxide coating was deposited by inductively coupled plasma chemical vapor deposition technology,and the gold coating was deposited by electron beam heating physical meteorological deposition technology.The radius of curvature of the tip after double-layer coating is 30-80nm,and the shape and coating meet the requirements,which can be stably prepared in batches.With the new probe,the contrast of TERS system is increased by three times and the enhancement factor is increased by one order of magnitude.Finally,the tip-enhanced Raman spectrum of SWCNTs was detected by self-made TERS system,and the complete spectrum was obtained.The characteristic peaks were obvious and the position was accurate.Through the analysis of the detection results,it is determined that the spectral resolution of the system is 20 nm,the contrast is 4.8,and the enhancement factor is 4×10~3.The enhancement effect of the new probe,the modulation of light field and the enhancement of the substrate were determined through the comparative experiments.The TERS system has high stability,resolution and detection sensitivity,which can provide a solid foundation for further study of Raman spectrum.