Effects Of Substrate Preprocessing On The Growth Of Silver Nano-film And Its Application In Trace Amount Detection

Raman spectrum is one of the most powerful techniques for the detection andanalysis of molecular structure since it was found in1927, and it has been used in awide range of applications such as biology, environment detection and material structureanalysis. In recent years, SERS (Surface enhanced Raman scattering) has been widelyused in the study of surface due to its high sensitivity, stability and high resolution, etc.And it attracts more and more attention in the field of trace amount detection. In thisresearch field, improving the morphology and properties of the SERS-active substratesis one of the hottest topics, and pretreatment, with no doubt, is a very important mean toachieve this purpose.In our work, silver nanorods array thin film was prepared with GLAD (glancingangle deposition) technique as the SERS-active substrate. The main of our researchwork is to improve the morphology and performance of the Ag thin film by the mean ofpretreatment. On one hand, proved by the relevant theory, the better the separation ofthe Ag nanorods is, the higher enhancing effect can be obtained. In order to improve theseparation of the Ag nanorods, we corroded Cu and Si wafers with acid and alkalirespectively, to obtain initial rough surfaces before we got the wafers deposited with Agvapor. On the other hand, by depositing a metal underlayer (such as Ag, Al, Ti and Cr)on the other side of the glass slides as a reflect layer, reflection electric field wasenhanced and resulted in higher sensitivity. As our experimental result showed, Cu andSi wafers with chemical cession did offer rougher surfaces for GLAD and the separationof the Ag nanorods had a relation with the corrosion time. With an optimal corrosiontime of20min, the Raman intensity offered by the SERS-active substrate of Si wafercorroded by alkali increased123%compared with the one without any treatment. In thelatter part of research, the Raman intensity was found to be positive with the reflectivity of thematerials when the Ag nanorods were deposited on the same side with the underlayer. But whenthe Ag nanorods were deposited on the other side of the Si wafer, the relationship between thesetwo was not clear.As the last part of this thesis, we also analyzed and compared Raman spectrums of someenvironmental pollutants, to set up a data base for the relevant research in this field.