以PAA为模板制备SERS基底及对三聚氰胺的检测

采用热蒸镀的方法直接在多孔氧化铝(porous anodic alumina,PAA)模板上蒸镀几微米的银膜,然后在HCl溶液中溶解掉模板,得到表面具有纳米尺度规则结构的银膜作为表面增强拉曼散射(surface-en-hanced Raman spectra,SERS)基底,并在该基底上测量了吡啶溶液(0.01 mol.L-1)的增强拉曼光谱,发现平均增强因子大于105。与直接在载玻片上蒸镀的银膜相比,具有纳米尺度规则结构银膜的增强效果提高了30倍。改变激发光功率测量吡啶的拉曼光谱,和普通拉曼散射一样,增强拉曼光谱的峰值强度随激发光强度线性变化,并在该基底上测量了三聚氰胺的拉曼光谱,发现在1 mW的激发功率下对于三聚氰胺的检出限为2.5 mg.L-1。

Using PAA template to fabricate SERS substrate and the SERS detection of melamine

The authors have got silver film with orderly arranged nanoparticles as the surface-enhanced Raman spectra (SERS) substrates using porous anodic alumina templates (PAA). A silver film (99.99%) with the thickness of several millimeters was thermally evaporated onto the PAA templates and the SERS substrate was got after removing the PAA templates in hydrochloric acid. SERS spectra of pyridine (0.01 mol x L(-1)) were measured on Renishaw 2000 Ramanscope with a He-Ne (632.8 nm) laser as an excitation source in backscattering geometry, and the average enhancement factors were more than 10(5). The authors compared SERS spectra of pyridine from the SERS substrates and from Ag film evaporated directly on glass slide, and the former was 30 times stronger than the latter. The authors got different SERS spectra of pyridine while changing the excitation laser power. It was found that the relationship between the peak intensity of SERS spectra and the excitation laser power was linear as the normal Raman spectrum. We used the substrates to detect melamine, 2.5 mg x L(-1) melamine solution could be recognized al though excitation laser power was below 1 mW.