Department of Chemistry and Richard E Smalley Institute for Nanoscale Science and Technology, Rice University, 6100 Main Street, Houston, Texas 77005, United States.
ACS Nano. 2012 Sep 25;6(9):8424-31. doi: 10.1021/nn3032744. Epub 2012 Sep 6.
A new method is demonstrated for measuring the length distributions of dispersed single-walled carbon nanotube (SWCNT) samples by analyzing diffusional motions of many individual nanotubes in parallel. In this method, termed "length analysis by nanotube diffusion" (LAND), video sequences of near-IR fluorescence microscope images showing many semiconducting SWCNTs are recorded and processed by custom image analysis software. This processing locates the individual nanotubes, tracks their translational trajectories, computes the corresponding diffusion coefficients, and converts those values to nanotube lengths. The deduced length values are then compiled into a histogram of lengths present in the sample. By using specific excitation wavelengths and emission filters, this analysis is performed on selected (n,m) structural species. The new LAND method has been found to give distributions in very good agreement with those obtained by conventional AFM analysis of the same samples. Because it is fluorescence-based, LAND monitors only semiconducting, relatively pristine SWCNTs. However, it is less sensitive to artifacts from impurities and bundled nanotubes than AFM or light scattering methods. In addition, samples can be analyzed with less time and operator attention than by AFM. LAND is a promising alternative method for characterizing length distributions of SWCNTs in liquid suspension.
一种新的方法被证明是用于测量分散的单壁碳纳米管（SWCNT）样品的长度分布，通过分析许多单个纳米管的扩散运动。在这种方法中，称为“纳米管扩散长度分析”（LAND），记录近红外荧光显微镜图像的视频序列，显示许多半导体 SWCNT，并通过定制的图像分析软件进行处理。此处理定位单个纳米管，跟踪它们的平移轨迹，计算相应的扩散系数，并将这些值转换为纳米管长度。然后将推断出的长度值编组成样品中存在的长度的直方图。通过使用特定的激发波长和发射滤波器，对选定的（n，m）结构物种进行此分析。已经发现，新的 LAND 方法给出的分布与通过对相同样品进行常规原子力显微镜分析获得的分布非常吻合。由于它是基于荧光的，LAND 仅监测半导体，相对原始的 SWCNT。然而，与 AFM 或光散射方法相比，它对杂质和捆扎纳米管的伪影的敏感性较低。此外，与 AFM 相比，样品可以用更少的时间和更少的操作人员关注进行分析。LAND 是一种有前途的替代方法，用于表征液体悬浮液中 SWCNT 的长度分布。
