设计了一种可重复使用的石墨烯-有序银纳米孔(GE-AgNHs）基底。 采用表面等离子体（surface plasmons, SPs）光刻技术在银膜上刻蚀出均匀的周期性纳米孔阵列; 用湿转移法将石墨烯转移至银纳米孔上形成有序石墨烯-银纳米孔复合结构。 石墨烯不仅提供了分子吸附平台, 也作为参考和校准层来提高表面增强拉曼的再现性。 银膜暴露于空气中时容易被氧化, 石墨烯覆盖于银膜表面可以隔绝空气, 从而达到减缓银膜氧化的目的。 分别采用光学显微镜、 场发射扫描电子显微镜（SEM）以及拉曼光谱表征。 从SEM表征结果可以看出银纳米孔均匀分布。 通过时域有限差分算法（finite-difference time-domain, FDTD）仿真模拟了不同孔径（220~280 nm）基底的电场分布(|E|)。 仿真结果表明: 电场强度随孔径的减小稍有增强, 在D=220 nm时取得最大电场强度Emax≈11 V·m-1, 计算得到增强因子为~1.46×104。 实验研究包括: 对GE-AgNHs基底本身进行拉曼mapping测试, 测试结果表明: 石墨烯D、 G和2D峰的RSD值分别为18.3%, 22.1%和19.8%, 具有较好的均匀性。 采用浓度为10-8~10-4 mol·L-1的结晶紫（crystal violet, CV）溶液进行拉曼测试并定量分析; 对10-8~10-4 mol·L-1范围内相对强度k(k=I@1 178/I@2D)进行指数拟合, 拟合度R2=97.7%, 若忽略10-4 mol·L-1的数据, 进行线性拟合, 拟合度达96.8%。 使用10-12 mol·L-1的罗丹明6G（rhodamine 6G, R6G）溶液作为探针分子, 硼氢化钠溶液作为清洗剂, 对GE-AgNHs基底进行SERS重复性实验。 从光学显微镜图以及拉曼光谱图中可以看出: 清洗前, GE上存在少量杂质; 清洗后, 得到干净GE拉曼信号。 清洗前后均可测到R6G的拉曼信号, 表明基底可重复性良好; 以773 cm-1为例, 拉曼强度维持50%。

We design a reusable graphene-ordered silver nanohole (GE-AgNHs) substrate. A uniform periodic nanopore array is etched on the silver film by surface plasmons (SPs) photolithography. Graphene is transferred to AgNHs by wet transfer method. Graphene not only provides a molecular adsorption platform, but also serves as a reference and calibration layer to improve surface-enhanced Raman reproducibility. When the silver film is exposed to the air, it is easily oxidized. The graphene covers the surface of the silver film to block the air, thereby slowing down the oxidation of the silver film. The substrate is characterized by optical microscopy, field emission scanning electron microscopy (SEM) and Raman spectroscopy. From the SEM characterization results, it can be seen that the silver nanopores are evenly distributed. Meanwhile, the electric field distribution (|E|) of different aperture bases is simulated by Finite-Difference Time-Domain (FDTD) simulation. The simulation results show that the electric field strength increases slightly with the decrease of the aperture. The maximum electric field strength Emax≈11 V·m-1 is obtained at D=220 nm, and the enhancement factor is calculated to be ~1.46×104. Many experiments were carried on. Firstly, we performed a Raman mapping test on the GE-AgNHs substrate. The results show that the RSD values of graphene D, G and 2D peaks are 18.3%, 22.1% and 19.8%, respectively, with good uniformity. Secondly, Raman test and quantitative analysis are carried on using crystal violet (CV) solution at concentrations of 10-8~10-4 mol·L-1. The exponential fitting of the relative intensity k(k=I@1 178/I@2D) in the range of 10-8~10-4 mol·L-1, the fitting degree R2=97.7%; if the data of 10-4 mol·L-1 is neglected, it performs a linear fit with a fit of 96.8%. Finally, SERS repeatability is performed on the GE-AgNHs substrate with a concentration of 10-12 mol·L-1 rhodamine 6G (R6G) solution as the probe molecule and sodium borohydride solution as the cleaning solution. It can be seen from the optical micrograph and the Raman spectrum that there is a small number of impurities on the GE before cleaning; after cleaning, a clean GE Raman signal is obtained. The Raman signal of R6G can be detected before and after cleaning, indicating that the substrate repeatability is good; the Raman intensity is maintained at 50% at 773 cm-1.