Kalbác Martin, Kavan Ladislav, Zukalová Markéta, Dunsch Lothar
Leibniz Institute of Solid-State and Materials Research, Group of Electrochemistry and Conducting Polymers, Helmholtzstr. 20, 01069 Dresden, Germany.
Small. 2007 Oct;3(10):1746-52. doi: 10.1002/smll.200700157.
C60 fullerene peapods and double-walled carbon nanotubes (DWCNTs) containing highly 13C enriched C60 and inner tubes, respectively, are studied using Raman spectroscopy and in situ Raman spectroelectrochemistry in order to follow the influence of 13C enrichment on the vibrational pattern of these carbon nanostructures. The Raman response of 13C60 after encapsulation in fullerene peapods differs from that of isotope-natural species, (Nat)C60. The Raman A(g)(2) mode of encapsulated 13C60 is upshifted in frequency compared to that of the (Nat)C60 peapods with the same filling factor. The chemical doping of 13C60 peapods (peapod = C(60)@SWCNT) with K-vapor leads to the downshift of the A(g)(2) mode, similar to the case of (Nat)C60 peapods. The 13C60 peapods were successfully transformed into DWCNTs, which confirms high filling of single-walled (SW) CNTs with 13C60. The DWCNTs exhibited distinctly downshifted G and D Raman modes for inner tubes, which proves that only inner tubes were enriched by 13C. The in situ Raman spectroelectrochemistry of (Nat)C60 exhibits strong anodic enhancement, while for 13C60 peapods the enhancement is only weak. On the other hand, the electrochemical charging of the inner-tube-labeled DWCNTs (13C(i)-DWCNTs) followed the behavior of ordinary (Nat)C(i)-DWCNTs as indicated by in situ Raman spectroelectrochemistry. In addition, the spectroelectrochemical behavior of the G mode of inner tubes in 13C(i)-DWCNTs is followed from the start of the electrochemical doping, which was not feasible for (Nat)C(i)-DWCNTs.
分别使用拉曼光谱和原位拉曼光谱电化学方法对含有高度富集(^{13}C)的(C_{60})的(C_{60})富勒烯豆荚和含有内管的双壁碳纳米管（DWCNTs）进行了研究，以便追踪(^{13}C)富集对这些碳纳米结构振动模式的影响。(^{13}C_{60})封装在富勒烯豆荚后，其拉曼响应与同位素天然物种((Nat)C_{60})不同。与具有相同填充因子的((Nat)C_{60})富勒烯豆荚相比，封装的(^{13}C_{60})的拉曼(A_{g}(2))模式频率发生了上移。用钾蒸汽对(^{13}C_{60})富勒烯豆荚（富勒烯豆荚(=C_{60}@SWCNT)）进行化学掺杂会导致(A_{g}(2))模式下移，这与((Nat)C_{60})富勒烯豆荚的情况类似。(^{13}C_{60})富勒烯豆荚成功转化为双壁碳纳米管，这证实了单壁（SW）碳纳米管被(^{13}C_{60})高度填充。双壁碳纳米管的内管表现出明显下移的(G)和(D)拉曼模式，这证明只有内管被(^{13}C)富集。((Nat)C_{60})的原位拉曼光谱电化学表现出强烈的阳极增强，而对于(^{13}C_{60})富勒烯豆荚，增强作用较弱。另一方面，如原位拉曼光谱电化学所示，内管标记的双壁碳纳米管（(^{13}C_{(i)}-DWCNTs)）的电化学充电遵循普通((Nat)C_{(i)}-DWCNTs)的行为。此外，从电化学掺杂开始就跟踪了(^{13}C_{(i)}-DWCNTs)内管(G)模式的光谱电化学行为，这对于((Nat)C_{(i)}-DWCNTs)是不可行的。
