Van der Waals'force-controlled nano Raman scattering spectroscopy

范德华力控制纳米拉曼散射光谱

基本信息

批准号：
16360034
负责人：
INOUYE Yasushi
金额：
$ 9.66万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360034/
关键词：
Near-field Raman spectroscopy Surface enhanced Raman Scattering Density functional formalism Carbon nanotube Local plasmon van der Waals'force Near-field optics Nanoscience technology ナノサイエンス・ナノテクノロジー

项目摘要

We found spectral shift of specific Raman band of carbon nanotubes (CNTs) when van der Waals's force is applied onto the CNTs. We measured Raman spectrum of single CNT bundle while applying stress on it with silver coated cantilever tip of atomic force microscope, and observed spectral change of Raman band of CNT in situ. When we apply stress from 0nN to 2.4nN successively, lower peak of G-band (〜1600cm-1) was red-shifted by 18cm-1. G-band reflects electric property of CNT and has two adjacent peaks. On the other hand, no peak shift was observed in higher peak of G-band. This phenomenon originates from the fact that two peaks are corresponding to the vibrational modes of different vibrational direction, and these two vibrational modes have different shearing stresses with respect to each other. Furthermore, we observed peak shift of radial breathing mode (RBM) around 200cm-1〜300cm-1 at most 5cm-1. RBM depends on the diameter of CNT. This peak shift can be attributed to the fact that the cross-section of CNT is deformed into ellipse shape by applied uniaxial stress on the CNT. We also observed intensity of all Raman band are enhanced when applying stress. This suggests that the band gap energy of CNT comes near to the resonance energy(2.33eV) because of the deformation of CNT along the long axis of CNT, thus contribution of resonant Raman effect is increased.We also performed vibrational calculation of molecule-metal cluster including a number of metal atom based on density functional theory. The calculation showed the experimentally observed band shift by complex formation mechanism is well reproduced if the metal cluster contains at least four Ag atoms.

当将范德华的力施加到CNT上时，我们发现了特异性拉曼碳纳米管（CNT）的光谱移动。我们测量了单个CNT束的拉曼光谱，同时用银色涂层的原子力显微镜的悬臂尖端在其上施加应力，并观察到CNT的Raman Rang频带的光谱变化。当我们成功地施加从0NN到2.4NN的应力时，G波段的较低峰（〜1600cm-1）被18cm-1红移。 G波段反映了CNT的电特性，并具有两个相邻的峰。另一方面，在G波段的较高峰中未观察到峰值变化。这种现象源于以下事实：两个峰与不同振动方向的振动模式相对应，而这两种振动模式相对于彼此具有不同的剪切应力。此外，我们观察到径向呼吸模式（RBM）在200cm-1至300cm-1左右的峰值变化最多5cm-1。 RBM取决于CNT的直径。这种峰值移位可以归因于以下事实：CNT的横截面通过在CNT上施加的单轴应力将CNT的横截面变形为椭圆形。我们还观察到在施加应力时，所有拉曼带的强度都会增强。这表明CNT的带隙能靠近共振能（2.33ev），因为CNT沿CNT的长轴变形，因此增加了共振拉曼效应的贡献。我们还对分子量群的振动计算进行了振动计算，包括基于密度功能理论的许多金属原子。计算表明，如果金属簇至少包含四个Ag原子，则可以很好地再现通过复合形成机制的实验观察到的带轮移位。