Single-wall carbon nanotubes and peapods investigated by EPR.
Single-wall carbon nanotubes and peapods investigated by EPR.
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DOI：
10.1039/b707936m
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发表时间：
2007-11
期刊：
影响因子：
--
通讯作者：
B. Corzilius;K. Dinse;K. Hata
中科院分区：
文献类型：
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作者：
B. Corzilius;K. Dinse;K. Hata
最近发展起来的超生长法制备的单壁碳纳米管(SWNT)具有电子顺磁共振(EPR)信号，这可以归因于巡回自旋。EPR结果表明，这种优质材料中的缺陷和催化剂浓度非常低。在这些条件下，EPR可以用来研究宽温度范围内电荷传输特性的细节，尽管这种材料在管径和手性方面仍然是非常“不均匀的”。在低于20K的温度范围内的非共振微波吸收表明，金属性质的管在费米能级上打开了一个小的能隙，这意味着向超导态的转变。使用部分填充了像N@C(60)这样的面内自旋探头的单壁碳纳米管，可以“从内部”研究这样的“豆荚”。连续波(CW)和脉冲EPR被用来研究管内的局域化动力学或检查与巡回电子的相互作用。采用不同方法生长的单壁碳纳米管，通过变温脉冲EPR实验，揭示了管径对富勒烯动力学的主要影响。这些差异可能与面内观察者的自旋和SWNT上的自旋之间的相互作用有关。
Single-wall carbon nanotubes (SWNT) prepared by the "super growth" method developed recently exhibit electron paramagnetic resonance (EPR) signals, which can be attributed to itinerant spins. EPR results indicate very low defect and catalyst concentrations in this superior material. Under these conditions EPR can be used to study details of charge transport properties over a wide temperature range, although the material is still very "heterogeneous" with respect to tube diameter and chirality. Non-resonant microwave absorption in the temperature range below 20 K is indicative for the opening of a small gap at the Fermi energy for tubes of metallic character, which is indicative for a transition into a superconducting state. Using SWNT filled partially with an endohedral spin probe like N@C(60), such "peapods" can be investigated "from the inside". Continuous-wave (cw) and pulsed EPR was used to investigate localization dynamics within the tubes or to check for interaction with itinerant electrons. Using SWNT grown by different methods, the dominant influence of tube diameter on fullerene dynamics was revealed by temperature dependent pulsed EPR experiments. These differences can be correlated with the interactions between the endohedral observer spin and spins on the SWNT.