Vobornik Dusan, Chen Maohui, Zou Shan, Lopinski Gregory P
Metrology Research Center, National Research Council, Ottawa, ON K1A 0R6, Canada.
Nanomaterials (Basel). 2023 Jan 24;13(3):477. doi: 10.3390/nano13030477.
In this work, we identify two issues that can significantly affect the accuracy of AFM measurements of the diameter of single-wall carbon nanotubes (SWCNTs) and propose a protocol that reduces errors associated with these issues. Measurements of the nanotube height under different applied forces demonstrate that even moderate forces significantly compress several different types of SWCNTs, leading to errors in measured diameters that must be minimized and/or corrected. Substrate and nanotube roughness also make major contributions to the uncertainty associated with the extraction of diameters from measured images. An analysis method has been developed that reduces the uncertainties associated with this extraction to <0.1 nm. This method is then applied to measure the diameter distribution of individual highly semiconducting enriched nanotubes in networks prepared from polyfluorene/SWCNT dispersions. Good agreement is obtained between diameter distributions for the same sample measured with two different commercial AFM instruments, indicating the reproducibility of the method. The reduced uncertainty in diameter measurements based on this method facilitates: (1) determination of the thickness of the polymer layer wrapping the nanotubes and (2) measurement of nanotube compression at tube-tube junctions within the network.
在这项工作中，我们识别出两个会显著影响单壁碳纳米管（SWCNT）直径的原子力显微镜（AFM）测量准确性的问题，并提出了一种减少与这些问题相关误差的方案。在不同作用力下对纳米管高度的测量表明，即使是适度的力也会显著压缩几种不同类型的单壁碳纳米管，导致测量直径出现误差，必须将这些误差最小化和/或校正。基底和纳米管的粗糙度也对从测量图像中提取直径所涉及的不确定性有很大影响。已开发出一种分析方法，可将与这种提取相关的不确定性降低到<0.1纳米。然后将该方法应用于测量由聚芴/单壁碳纳米管分散体制备的网络中单个高度富集半导体纳米管的直径分布。使用两台不同的商用原子力显微镜对同一样品测量得到的直径分布之间取得了良好的一致性，表明该方法具有可重复性。基于此方法的直径测量中降低的不确定性有助于：（1）确定包裹纳米管的聚合物层的厚度，以及（2）测量网络内管 - 管连接处纳米管的压缩情况。
