中文摘要：

采用一种高活性的纳米银膜作为表面增强拉曼散射（SERS）基底,以近红外激光（785nm）作为激发光源,对胞嘧啶核苷（胞苷）水溶液（10-2~10-8 mol·L-1）进行了近红外表面增强拉曼散射（NIR-SERS）光谱检测。实验结果表明,当胞苷水溶液浓度等于或低于10-7 mol·L-1时,可在300~2 000cm-1范围内获得信噪比较好的NIR-SERS光谱。将胞苷水溶液（10-2~10-5 mol·L-1）分别滴在10片不同的纳米银薄膜上进行检测,结果表明该纳米银膜体现出了较好的光谱重现性。通过对纳米银膜表面形貌进行表征发现聚乙烯醇（PVA）包覆的纳米银颗粒在铝片表面形成＂草状＂结构。并通过对吸附了胞苷分子的纳米银膜进行紫外-可见光反射光谱检测,发现在800nm处出现等离子共振峰。因此采用785nm的近红外激光作为激发光时,该体系能够体现出强烈的表面等离子共振（surface plasmon resonance,SPR）特性。同时采用DFTB3LYP/6-311G对胞苷分子进行了拉曼光谱计算,计算所采用入射光波长为785nm,通过计算结果与实验测得的胞苷固体的拉曼光谱对比发现在300~2 000cm-1范围内两者匹配得较好,进而对其振动进行了归属。最后通过比较胞苷的拉曼光谱和NIR-SERS光谱对胞苷分子在纳米银膜上的可能吸附方式进行了分析。分析结果表明胞苷分子主要为其核糖部分吸附纳米银颗粒上,同时该分子的17NH2基团可能靠近局域电磁场增强区域。

英文摘要：

The polyvinyl alcohol（PVA）protected silver glass-like nanostructure（PVA-Ag-GNS）with high surface-enhanced Raman scattering（SERS）activity was prepared and employed to detect the near-infrared surface enhanced Raman scattering（NIR-SERS）spectra of cytidine aqueous solution（10-2~10-8 mol·L-1）.In the work,the near-infrared laser beam（785nm）was used as the excitation light source.The experiment results show that high-quality NIR-SERS spectra were obtained in the ranges of 300 to 2 000cm-1 and the detection limit of cytidine aqueous solution was down to 10-7 mol·L-1.Meanwhile,the PVA-Ag-GNS shows a high enhancement factor（EF）of~108.In order to test the optical reproducibility of PVA-Ag-GNS,ten samples of cytidine aqueous solution（10-2~10-5 mol·L-1）had been dropped onto the surface of PVA-Ag-GNS respectively.Meanwhile,these samples were measured by the portable Raman spectrometer.As a result,the PVA-Ag-GNS demonstrated good optical reproducibility in the detection of cytidine aqueous solution.In addition,to explain the reason of enhancement effect,the ultraviolet-visible（UV-Vis）extinction spectrum and scanning electron microscope（SEM）of cytidine molecules adsorbed on the surface of PVA-Ag-GNS were measured.There is plasmon resonance band at 800 nm in the UV-Vis extinction spectrum of the compound system.Therefore,when the near-infrared laser beam（785nm）was used as excitation light source,the compound system may produce strongly surface plasmon resonance（SPR）.According to the SEM of PVA-Ag-GNS,there are much interstitial between the silver nanoparticles.So NIR-SERS is mainly attributed to electromagnetic（EM）fields associated with strong surface plasmon resonance.At last,the geometry optimization and pre-Raman spectrum of cytidine for the ground states were performed with DFT,B3 LYP functional and the 6-311 Gbasis set,and the near-infrared laser with wavelength of 785 nm was employed in the pre-Raman spectrum calculation process.The calculation results without imaginar