摘要
表面增强拉曼散射(SERS)光谱技术是一种高灵敏度的检测技术,已在社会发展的多个领域显示出潜在的应用前景。SERS活性基底的大面积、低成本、可控制备是表面增强拉曼散射光谱学研究领域的热点之一。利用溶液法将直径小于5nm的金纳米团簇旋涂成膜,调控退火温度和时间,将金纳米团簇融合组装成随机分布的金纳米岛。由于融合组装过程在150~210℃范围缓慢,控制条件可实现具有高密度增强"热点"的SERS基底,方法简单、成本低廉、面积大、均匀性高。我们利用该方法可重复性获得了性能优良的SERS基底。该基底对表面吸附的单分子层,具有强烈的表面增强拉曼散射光谱响应,150~210℃退火样品的宏观增强因子106~107量级。研究表明:相同条件下150~180℃退火,金纳米团簇首先融合成直径10~20nm细小金纳米岛;退火温度190~210℃时,形成10~20nm细小金纳米岛与50~70nm金纳米岛混合并存的现象。拉曼光谱表征显示:大、小金纳米岛混合并存样品的宏观增强因子高于细小金纳米岛组成的样品。经220℃退火后,金纳米团簇完全融合成直径50~100nm的金纳米岛,岛间距也随之增大,导致纳米岛之间的电磁场强度呈指数衰减,220℃退火的样品具有较低的增强因子。本论文揭示了金纳米团簇的缓慢自组装机制,分析了金纳米岛的形貌与表面增强拉曼散射光谱的关系,为该基底的应用研究奠定基础。
Surface-enhanced Raman scattering （SERS） has been applied in a range of fields for its high sensitivity and its poten- tial applications in several critical social areas. Reproducible fabricating the SERS substrates in large scale and low cost has been one of the hot topics in SERS researches. In this paper, we assembled the solution processed gold nano clusters with the diame- ter less than 5 nm into the randomly distributed gold-nanoislands by optimizing the annealing process. We found that the assemb- ling process was slow and could be finely controlled as the annealing temperaturewas within the range of 150-210℃. By con- trolling the assembling process, we can reproducibly fabricate a kind of homogeneous SERS substrate with high density of ＂hot spots＂ in large area. These SERS substrates had intense surface enhanced Raman scattering to the monolayer adsorbed on the surface of the gold-nanoislands, and yielded a global enhancement factor as large as 106-107 for the samples annealed at 150-210℃. We found that, under the same conditions, the gold nano clusters were firstly fused into tiny gold-nanoislands with the diameter of 10-20 nm as the annealing temperature was within the range of 150-180℃. As the annealing temperature was increased to 190-210℃, the matrix of tiny gold-nanoislands （10-20 nm） and large gold nanoislands （50-70 nm） could be formed. The spectral characterization has shown that the samples consist of the matrix of tiny and large gold-nanoislands have a higher global enhancement factor than the samples consist of barely tiny gold-nanoislands. At 220℃, the gold nanoclusters completely fused into large gold-nanoislands. However, the gaps between the large gold-nanoisland also increased with the fusing process, which induced an exponential decay of the intensity of the electromagnetic field between the gold-nanoistands. As a result, the samples annealed at 220℃ has the lowest SERS enhancement factor. In this work, we demonstrated the mechanism of how low-temperature anne
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2018年第1期87-92,共6页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(11304005)
北京市教委项目(KM201510005030)资助
关键词
表面增强拉曼散射
金纳米团簇
金纳米岛
自组装
Surface enhanced Raman scattering
Gold nanocluster
Goldnanoislands
Self-assembling
