Tsyboulski Dmitri A, Bachilo Sergei M, Kolomeisky Anatoly B, Weisman R Bruce
Department of Chemistry, Richard E. Smalley Institute for Nanoscale Science and Technology, and Center for Biological and Environmental Nanotechnology, Rice University, 6100 Main Street, Houston, Texas 77005, USA.
ACS Nano. 2008 Sep 23;2(9):1770-6. doi: 10.1021/nn800364r.
Near-infrared fluorescence videomicroscopy has been used to study simultaneously the translational and rotational diffusion of individual semiconducting single-walled carbon nanotubes (SWCNTs) in aqueous suspension. Analysis of translational trajectories revealed diffusion coefficient values from approximately 0.3 to 6 microm(2)/s. The nanotube lengths deduced from these values ranged between approximately 130 nm and 6 microm. From the minor bending motions observed in individual nanotubes several micrometers in length, we confirmed that the shorter SWCNTs of primary interest here can be considered to be rigid rods under normal conditions. Because the nanotubes act as highly rigid, photostable, steady, and anisotropic fluorophores, it was possible to monitor their rotational reorientations through fluctuations in emission intensity under linearly polarized excitation. The magnitudes of observed orientational fluctuations varied substantially among individual nanotubes. These magnitudes correlated strongly with translational diffusion coefficient, reflecting the length dependence of both types of motions. Combined translational and rotational measurements also revealed the influence of local environment on nanotube mobility.
近红外荧光视频显微镜已被用于同时研究单个半导体单壁碳纳米管（SWCNT）在水悬浮液中的平移扩散和旋转扩散。对平移轨迹的分析揭示了扩散系数值约为0.3至6微米²/秒。从这些值推导出的纳米管长度在约130纳米至6微米之间。从在几微米长的单个纳米管中观察到的微小弯曲运动，我们证实了这里主要关注的较短SWCNT在正常条件下可被视为刚性棒。由于纳米管作为高度刚性、光稳定、稳定且各向异性的荧光团，通过线性偏振激发下发射强度的波动来监测其旋转重取向成为可能。观察到的取向波动幅度在各个纳米管之间有很大差异。这些幅度与平移扩散系数密切相关，反映了两种运动类型的长度依赖性。平移和旋转的联合测量还揭示了局部环境对纳米管迁移率的影响。
