TiN-Ag@Ag SERS基底制备及其对腺嘌呤的检测性能与增强机制研究

Preparation of TiN-Ag@Ag Surface-enhanced Raman Spectroscopy Substrate and Its Performance and Enhancement Mechanism for Adenine Detection

该文制备了TiN@Ag溶胶、TiN-Ag薄膜、TiN-Ag@Ag溶胶3种复合基底对腺嘌呤进行表面增强拉曼光谱(SERS)检测,并对拉曼增强效应进行研究。结果显示,与理论峰位相比,腺嘌呤的SERS图峰位发生偏移,可能是腺嘌呤吸附在增强基底上时分子构型和偶极距发生了改变(理论计算中过多的电子和外部溶剂的参与也会引起峰位偏移)。研究发现TiN-Ag@Ag溶胶基底上腺嘌呤的信号最强,这是因为该基底不仅具有TiN薄膜与Ag纳米颗粒发生共振耦合出现的可使SERS活性明显提高的“热点”,还存在Ag纳米颗粒聚集在Ag纳米棒之间形成的纳米间隙产生的更多“热点”。利用TiN-Ag@Ag溶胶基底对腺嘌呤进行灵敏检测,检出限可达10^(-5)mol/L。并通过紫外光电子能谱结合高斯软件中密度泛函理论和时域有限分差法,对各基底的增强机制进行了分析。

Three composite substrates,TiN@Ag sol,TiN-Ag film and TiN-Ag@Ag sol were prepared for surface-enhanced Raman spectroscopy(SERS) detection of adenine,and the enhancement effect of Raman performance was studied and analyzed.It was found that the peak position of the adenine SERS spectrum was somewhat shifted compared with the theoretical one,where the molecular configuration and dipole moment changed probably when adenine was adsorbed on the enhanced substrate.Meanwhile,the participation of excessive electrons and external solvents in the theoretical calculation might cause peak shift.It was also found that the adenine signal on the TiN-Ag@Ag sol substrate was the strongest since the substrate not only has “hot spots” that can significantly improve the SERS activity due to the resonance coupling between the TiN film and silver nanoparticles,but also has more “hot spots”provided by the Ag nanoparticles on the TiN-Ag@Ag sol substrate aggregated between the Ag nanorods on TiN to form a nano-band gap.Furthermore,TiN-Ag@Ag sol substrate was applied to the sensitive detection of adenine,with a detection limit of 10^(-5)mol/L.Finally,the enhancement mechanisms for each substrate were analyzed by UV photoelectron spectroscopy combined with Gaussian and FDTD calculations.