Odom Teri Wang, Huang Jin-Lin, Lieber Charles M
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Ann N Y Acad Sci. 2002 Apr;960:203-15.
Single-walled carbon nanotubes (SWNTs) are ideal systems for investigating fundamental properties in one-dimensional electronic systems and have the potential to revolutionize many aspects of nano/molecular electronics. Scanning tunneling microscopy (STM) has been used to characterize the atomic structure and tunneling density of states of individual SWNTs. Detailed spectroscopic measurements showed one-dimensional singularities in the SWNT density of states for both metallic and semiconducting nanotubes. The results obtained were compared to and agree well with theoretical predictions and tight-binding calculations. SWNTs were also shortened using the STM to explore the role of finite size, which might be exploited for device applications. Segments less than 10 nm exhibited discrete peaks in their tunneling spectra, which correspond to quantized energy levels, and whose spacing scales inversely with length. Finally, the interaction between magnetic impurities and electrons confined to one dimension was studied by spatially resolving the local electronic density of states of small cobalt clusters on metallic SWNTs. Spectroscopic measurements performed on and near these clusters exhibited a narrow peak near the Fermi level that has been identified as a Kondo resonance. In addition, spectroscopic studies of ultrasmall magnetic nanostructures, consisting of small cobalt clusters on short nanotube pieces, exhibited features characteristic of the bulk Kondo resonance, but also new features due to their finite size.
单壁碳纳米管（SWNTs）是研究一维电子系统基本性质的理想体系，并且有可能彻底改变纳米/分子电子学的许多方面。扫描隧道显微镜（STM）已被用于表征单个SWNTs的原子结构和态隧穿密度。详细的光谱测量显示，金属和半导体纳米管的SWNT态密度中都存在一维奇点。所获得的结果与理论预测和紧束缚计算进行了比较，结果吻合良好。还使用STM缩短了SWNTs，以探索有限尺寸的作用，这可能会用于器件应用。长度小于10 nm的片段在其隧穿光谱中表现出离散的峰，这些峰对应于量子化能级，其间距与长度成反比。最后，通过空间分辨金属SWNTs上小钴簇的局部电子态密度来研究磁性杂质与局限于一维的电子之间的相互作用。在这些簇上及其附近进行的光谱测量在费米能级附近显示出一个窄峰，该峰已被确定为近藤共振。此外，由短纳米管片段上的小钴簇组成的超小磁性纳米结构的光谱研究显示出体近藤共振的特征，但也因其有限尺寸而呈现出新的特征。
