Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
Nanoscale. 2018 Mar 28;10(12):5449-5456. doi: 10.1039/c7nr08631h. Epub 2018 Mar 1.
We present a systematic study on the fabrication, characterization and high temperature surface enhanced Raman spectroscopy (SERS) performance of SiO coated silver nanoparticles (Ag@SiO) on a flat substrate, aiming to obtain a thermally robust SERS substrate for monitoring high temperature reactions. We confirm that a 10-15 nm SiO coating provides a structure stability up to 900 °C without significantly sacrificing the enhancement factor, while the uncoated particle cannot retain the SERS effect above 500 °C. The finite difference time domain (FDTD) simulation results supported that the SiO coating almost has no influence on the distribution of the electric field but only physically trapped the most enhanced spot inside the coating layer. On this thermally robust substrate, we confirmed that the SERS of horizontally aligned single walled carbon nanotubes is stable at elevated temperatures, and demonstrate an in situ Raman monitoring of the atmosphere of the annealing process of nanodiamonds, in which the interconverting process of C-C bonds is unambiguously observed. We claim that this is a first experimental proof that the high temperature SERS effect can be preserved and applied in a chemical reaction at temperature above 500 °C. This versatile substrate also enables novel opportunities for observing growth, etching, and structure transformation of many 0D and 2D nano-materials.
我们对在基底上制备、表征和高温表面增强拉曼光谱（SERS）性能的 SiO 涂层银纳米粒子（Ag@SiO）进行了系统研究，旨在获得一种用于监测高温反应的热稳定 SERS 基底。我们证实，10-15nm 的 SiO 涂层在不显著牺牲增强因子的情况下提供高达 900°C 的结构稳定性，而未涂层的颗粒在 500°C 以上不能保留 SERS 效应。有限差分时间域（FDTD）模拟结果支持 SiO 涂层几乎对电场分布没有影响，只是物理上捕获了涂层内部最增强的点。在这种热稳定的基底上，我们证实了水平取向的单壁碳纳米管的 SERS 在高温下是稳定的，并展示了纳米金刚石退火过程中气氛的原位拉曼监测，其中明确观察到了 C-C 键的相互转化过程。我们声称，这是第一个实验证明高温 SERS 效应可以在 500°C 以上的化学反应中得到保留和应用。这种多功能基底还为观察许多 0D 和 2D 纳米材料的生长、刻蚀和结构转变提供了新的机会。
