Study On Controlled Fabrication Of AuNPAs-AuNRs Composite SERS Substrate And Key Technologies Of Explosive Detection

In order to meet the needs of highly sensitive detection of TNT molecules in gas-phase and liquid-phase environments,this paper carried out research on the controlled process preparation of Au NPAs-Au NRs composite substrates,and proposed the scheme for the detection of TNT molecules in gas-phase and liquid-phase environments based on the SERS technique.The main research work is as follows:1.The design of the composite SERS substrate structure and the simulation of the electromagnetic characteristics were carried out.A composite SERS substrate combining Au NPAs solid substrates with Au NRs nanoparticles was designed to address the advantages and disadvantages of current SERS substrates.Based on the finite difference time domain algorithm,the electromagnetic field enhancement characteristics of Au NPAs substrates,Au NRs nanoparticles and composite SERS substrates were simulated and calculated respectively and the generation mechanism of SERS hotspots and distribution sites of the three substrates were analyzed.The results showed that new SERS hotspots were generated between the Au NPAs solid substrate and the Au NRs nanoparticles,where the SERS hotspots generated by the connection of the Au NRs nanoparticles with end binding to the Au NPAs solid substrate were the strongest.2.A study on the preparation process and performance of composite SERS substrates was carried out.Based on the tilted angle deposition technique,Au NPAs solid substrates were prepared and characterized.Based on the seed growth method,Au NRs nanoparticles were prepared,and the morphological and spectral properties of Au NRs nanoparticles were analyzed.Then the combination of Au NPAs solid substrates and Au NRs nanoparticles was explored to achieve structural optimization of composite SERS substrates.The performance,homogeneity and reproducibility of the composite SERS substrates were investigated using R6G as the probe molecule.The results showed that the composite SERS substrates have good SERS performance and potential practical applications.3.Screening of TNT capture molecules and direct SERS detection studies were carried out.In order to achieve effective adsorption of TNT on composite SERS substrates,a screening study of TNT capture molecules was carried out using acoustic surface wave devices as a screening tool,the preparation process of acoustic surface wave devices with different wavelengths was explored,and the mass loading effect of acoustic surface wave devices was analyzed.Three TNT capture molecules（PATP,cysteine,cysteamine）were screened using an 8μm wavelength acoustic surface wave device,and then the screened capture molecules were modified onto a composite SERS substrate.With direct detection,the detection limit can reach 10.05ppb for TNT gas and 10^-4 mol/L for TNT solutions.4.A study on highly sensitive indirect detection of TNT based on SERS technology was carried out.Due to the low sensitivity of direct detection of TNT solutions using composite SERS substrates,the principle of highly sensitive indirect detection of TNT was designed and the feasibility of this indirect detection method was verified experimentally.In addition,the sensitivity and selectivity of the TNT solution was investigated and it was shown that a highly sensitive(4.4×10^-11mol/L)and specific detection of TNT molecules could be achieved with the help of the indirect detection method.