Investigation Of On-line Detection Based On Surface Enhanced Raman Spectroscopy

Surface enhanced Raman spectroscopy (SERS) has been developed successfully asone of powerful spectroscopic tools for detecting and indentifying trace amounts ofchemicals. As it was known, the selection of the appropriate substrate as an enhancementsource was essential to obtain favorable SERS signal. Normally, the optimal substratesshould match the requirements involving the uniformity, cleanability, regeneration andgenerality. It was benifical to obtain the reproducible data for the investigation of complexenhancement mechanisms and qualitative or quantitative analysis. In this dissertation, afacile approach was developed to prepare different kinds of recycling and high effectiveSERS substrates, and its application in the on-line detection was explored. The main resultswere listed below:1. Improved the procedure for the preparation of Au nanoparticles and surfaceattached inert layer. The pinhole-free shell isolated nanoparticles of Au@SiO2wasobtained. The uniform, compact core-shell isolated nanoparticles monolayer film wasfabricated by the film formation at liquid/liquid interface. Au nanoparticles with diameterof about110nm were prepared by hydroquinone seed growth method. By usingmercaptopropyl trimethoxysilane as coupling agent and controlling the hydrolysis duration,core-shell isolated nanoparticles of Au@SiO2with shell thickness of about4nm wereprepared. The monolayer of Au@SiO2film was served as the SERS substrate for thedetection of dyestuff in the toxic chilli.2. Developed the on line recycling SERS detection technique. The SERS activecapillary was fabricated by immoblizing the Au nanoparticles onto the inner wall followedwith the attachment of thin layer of silica. The recycling SERS detection was achieved byoptimizing the uniformity and on line continuous elution technology. The results revealedthat there was little change in performance of the SERS substrate after ten times recycles.By using thiophenol, mercaptobenzonic acid,4-nitrothiophenol,1,4-benzenedithiol asprobing molecules, the capability for regeneration was explored. The relationship between the SERS intensities and the concentration of the probe was investigated to built thequasi-quantitative curves by using the thiophenol and malachite green as the flowingphase.This method could be developed as the real time on line anslysis technique with highthroughput.3. Two kinds of soft SERS substrates were fabricated with facile routine and lowconsume. The uniform nanoparticles film was adhered and assembled onto the inner wallof the tube after the centrifugation. The SERS results indicated that the film possessedoptimal SERS effect and reasonable regeneration. The on line detection of poisonous gaswas explored based on this substrate. The nanoparticles transfer technique were developed,in which the tape was adhered and peeled off from the solid substrate with numerous Aunanoparticles to produce SERS active tape. The rapid sampling analysis on a solid surfacewas reached by using the adhesive capability of tape.