Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124, P. R. China.
Nanoscale. 2014 May 21;6(10):5099-105. doi: 10.1039/c4nr00161c.
Highly homogeneous surface-enhanced Raman scattering (SERS) substrates were produced on the centimeter scale by annealing solution-processed gold nanoparticles into plasmonic nanoislands. The average size and separation of the nanoislands are controlled by tuning the annealing temperature. SERS measurements yield a global enhancement factor as large as 10(7) over an area of 2 × 2 cm(2) for samples annealed at temperatures ranging from 150 to 200 °C. Spectral "mapping" of the SERS signal shows a homogeneous distribution of hotspots with high contrast over the entire substrate. The relative standard deviation of the SERS signal is less than 5.4% over an area of 50 × 50 μm(2). Theoretical simulations show strong dependence of the near-field electromagnetic enhancement on the size and the separation gap of the gold nanoislands. Both average gap size and average nanoisland size increase with an increase in annealing temperature. Intensive plasmonic coupling between the adjacent gold nanoislands leads to broadband resonance for samples annealed at 150 and 200 °C; thus, the laser excitation within the spectrum of plasmon resonance at 633 or 785 nm produced significantly enhanced SERS for 4-mercaptopyridine molecules modified on the gold nanoislands.
通过将溶液处理的金纳米粒子退火成等离子体纳米岛，在厘米尺度上制备出高度均匀的表面增强拉曼散射（SERS）衬底。通过调整退火温度，可以控制纳米岛的平均尺寸和分离。对于在 150 至 200°C 温度范围内退火的样品，SERS 测量得到的全局增强因子高达 10(7)，面积为 2×2cm(2)。SERS 信号的“映射”显示，在整个衬底上热点具有高对比度的均匀分布。在 50×50μm(2)的区域内，SERS 信号的相对标准偏差小于 5.4%。理论模拟表明，近场电磁增强强烈依赖于金纳米岛的尺寸和分离间隙。随着退火温度的升高，平均间隙尺寸和平均纳米岛尺寸均增加。在 150 和 200°C 退火的样品中，相邻金纳米岛之间的强烈等离子体耦合导致宽带共振；因此，在等离子体共振光谱范围内的激光激发在 633 或 785nm 产生了显著增强的金纳米岛上修饰的 4-巯基吡啶分子的 SERS。
