论文标题
底物对尖端增强的拉曼光谱的影响---频域模拟和石墨烯测量的比较
Impact of Substrate on Tip-enhanced Raman Spectroscopy --- A Comparison of Frequency Domain Simulations and Graphene Measurements
论文作者
论文摘要
尖端增强的拉曼光谱（TERS）已达到纳米空间分辨率，以在环境条件下进行测量，并在超高真空吸尘器下进行亚纳米分辨率。已经获得了超分辨率（超出尖端顶点直径）TER，主要是在间隙模式配置中，在该配置中，导电基板将电场定位。在这里，我们提出了实验和理论上的探索，以探索负责光谱增强的现场分布。我们使用$ 40 \ pm 10 \ \ text {nm} $的金色技巧，以测量石墨烯上的ters，这是一个坐在不同底物上的空间隔离的二维样品，坐在不同的底物上：（i）玻璃，（ii）一层薄薄的金色和（iii）覆盖有$ 12 \ \ \ \ \ \ \ \ fext {分辨率是在环境条件下实现的。超分辨率是由于耦合的尖端样品 - 基底系统产生的现场配置，该系统表现出非平凡的空间表面分布。对于非差距和间隙模式配置，现场分布和对称选择规则不同。这会影响取决于拉曼模式对称性和底物结构的整体增强。
Tip-enhanced Raman spectroscopy (TERS) has reached nanometer spatial resolution for measurements performed at ambient conditions and sub-nanometer resolution at ultra high vacuum. Super-resolution (beyond the tip apex diameter) TERS has been obtained, mostly in the gap mode configuration, where a conductive substrate localizes the electric fields. Here we present experimental and theoretical TERS to explore the field distribution responsible for spectral enhancement. We use gold tips of $40\pm 10 \ \text{nm}$ apex diameter to measure TERS on graphene, a spatially delocalized two-dimensional sample, sitting on different substrates: (i) glass, (ii) a thin layer of gold and (iii) a surface covered with $12\ \text{nm}$ diameter gold spheres, for which $6\ \text{nm}$ resolution is achieved at ambient conditions. The super-resolution is due to the field configuration resulting from the coupled tip-sample-substrate system, exhibiting a non-trivial spatial surface distribution. The field distribution and the symmetry selection rules are different for non-gap vs. gap mode configurations. This influences the overall enhancement which depends on the Raman mode symmetry and substrate structure.
