Chu Ming-Wen, Sharma Pradeep, Chang Ching-Pin, Liou Sz Chian, Tsai Kun-Tong, Wang Juen-Kai, Wang Yuh-Lin, Chen Cheng Hsuan
Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.
Nanotechnology. 2009 Jun 10;20(23):235705. doi: 10.1088/0957-4484/20/23/235705. Epub 2009 May 19.
Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (approximately 30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at approximately 3.5 eV (approximately 355 nm) and approximately 7.0 eV (approximately 177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.
此前对银中表面等离子体激元的研究主要集中在其在可见光谱范围内的激发。我们使用0.2纳米电子束的扫描透射电子显微镜结合电子能量损失谱，在紫外光谱范围内对生长在硅上的单个银纳米颗粒（约30纳米）中的表面等离子体激元进行了光谱和空间探测。这些纳米材料在约3.5电子伏特（约355纳米）和约7.0电子伏特（约177纳米）处分别呈现出尖锐和宽泛的表面等离子体激元共振，相关的光谱计算确定了它们的多极特性。还绘制了纳米颗粒上表面等离子体激元的近场分布，揭示了3.5电子伏特激发的主要偶极性质，在纳米物体的一端有明显的近场增强。所揭示的近场增强在等离子体学和分子传感方面具有潜在应用。
