Research On SERS Substrate Based On Fano Resonance

Raman spectroscopy,as a unique "fingerprint" of substances,can achieve the purpose of qualitative analysis of substances.Surface-enhanced Raman spectroscopy（SERS）technology is widely used in the fields of cultural relics and criminal investigation identification,food safety,medical and pharmaceutical fields.SERS detection relies on a high-gain SERS substrate,and Fano resonance provides a new idea for SERS detection by virtue of its high near-field enhancement.In this thesis,a low-cost and high-efficiency Fano resonance-based SERS substrate was proposed,and its trace detection capability as a SERS-enhanced substrate was evaluated from numerical simulation,experimental preparation to performance testing.The main contents are as follows:First,a gold nanosphere dimer-dielectric-gold film sandwich structure is proposed,which can generate magnetic mode-based Fano resonance.The Fano resonance can be tuned efficiently from visible to near infrared wavelength by changing the size of the gold nanospheres and the thickness of the dielectric layer.The proposed structure is sensitive to the polarization direction of the excitation light.The flexible tuning,high absorption and low loss properties make this structure have great potential for surface-enhanced Raman scattering,but due to the self-assembly of heterodimers and the difficulty of controlling and realizing precise dielectric layer thickness,this Fano structure only stays in the theoretical stage.Secondly,combined with the experimental conditions,a heptamer structure of gold nanospheres based on Fano resonance was realized.First,the optical properties of gold nanosphere heptamers were calculated,and the Fano resonance mechanism of the structure was analyzed.The optimal material and size of the heptamer is determined.Then,the preparation of the heptameric structure was realized by the template-assisted and interface self-assembly method.The principle of the whole self-assembly process,the influence of the reagents on the interface self-assembly results and the final parameters were introduced.Finally,the absorption and scattering spectra of the prepared SERS substrate was tested and compared with the simulation results.The performance of the heptameric SERS substrate formed by the silicon-based template and the AAO template was tested and compared.The Raman enhancement effects of various oligomer SERS substrates composed of different numbers of gold nanospheres formed by AAO templates with different sizes were compared,and the conclusion that the oligomer based on Fano resonance was better than that based on local plasmon resonance was verified.The detection sensitivity of the Fano resonance-based SERS chip was analyzed,and it was found that the detection limit for 4-ATP was as low as 10-16 M.It can be predicted that this substrate may become an effective and low-cost detection method for molecular trace detection.Sensitive detection tool.