摘要
运用密度泛函理论, 对截面为三元环的有限长SiO2纳米管进行了研究. 核磁共振(NMR)的结果表明, 随着纳米管层数的增加, 29Si和17O原子的各向同性化学屏蔽张量σiso和各向异性化学屏蔽张量Δσ由两端向中间振荡直至趋于稳定值. 对长度大于一定数值的有限长纳米管, 中间层上原子的σiso和Δσ值可作为更长的或无限长SiO2纳米管的理论预测值, 这些结果对如何选取合理的有限长纳米管模型来研究无限长结构具有一定的指导意义.
Finite length SiO2 nanotubes composed of a three-membered ring （3MR） cross section were investigated by density functional theory. Nuclear magnetic resonance （NMR） results reveal that the isotropic chemical shielding tensor （σiso） and anisotropic chemical shielding tensor （△σ） of the SiO2 nanotubes oscillate from the terminal end to the intermediate part of the structures with an increase in nanotube lengths, and they tend to reach different stable values. When the length is greater than certain value the σno and △σ values obtained from the intermediate part of the finite length nanotube can be used for theoretical predictions of long or infinite length nanotubes. Hence, this investigation is a guide for the selection of reasonable finite length nanotubes to model infinite length nanotubes.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2011年第9期2227-2232,共6页
Acta Physico-Chimica Sinica
基金
国家杰出青年科学基金(50925103)资助项目~~
关键词
纳米管核磁共振
各向同性
各向异性
化学屏蔽
尺寸效应
Nanotube
Nuclear magnetic resonance
Isotropy
Anisotropy
Chemical shielding
Size effect
