Carbon atoms are counted at near atomic-level precision using a scanning transmission electron microscope calibrated by carbon nanocluster mass standards. A linear calibration curve governs the working zone from a few carbon atoms up to 34,000 atoms. This linearity enables adequate averaging of the scattering cross sections, imparting the experiment with near atomic-level precision despite the use of a coarse mass reference. An example of this approach is provided for thin layers of stacked graphene sheets. Suspended sheets with a thickness below 100 nm are visualized, providing quantitative measurement in a regime inaccessible to optical and scanning probe methods.
@article{arxiv.1012.0651,
title = {Calibrating the atomic balance by carbon nanoclusters},
author = {Fengqi Song and Xuefeng Wang and Rebecca C. Powles and Longbing He and Nigel A. Marks and Shifeng Zhao and Jianguo Wan and Zongwen Liu and Jianfeng Zhou and Simon Ringer and Min Han and Guanghou Wang},
journal= {arXiv preprint arXiv:1012.0651},
year = {2015}
}