概括
碳纳米管比其他碳形式具有更高的磁性易感性,这表明它具有类似石墨的带结构. C(60) 富勒里特显示了与分子排序相关的磁性易感性跳跃.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 材料科学 材料科学 材料科学
- 纳米技术纳米技术
背景情况:
- 元素碳存在于各种形式,包括钻石,石墨,富勒伦 (如C60) 和纳米管.
- 碳纳米管和C(60) 富勒赖特的磁性特性相比其他碳类物质的理解程度较低.
- 磁性易感性为电子带结构和分子间相互作用提供了洞察力.
研究的目的:
- 为了研究和比较碳纳米管和C(60) 富勒里特的磁性易感性.
- 阐明这些碳形式中分子结构,分子间相互作用和磁性之间的关系.
- 了解纳米管的电子带结构和顺序过渡对富勒里特性质的影响.
主要方法:
- 对碳纳米管的磁感应度的测量.
- 高分辨率的磁感应度测量C(60) 富勒里特在它的方向顺序过渡附近.
- 分析易感性数据以推断带结构和合作效应.
主要成果:
- 与其他元素碳形式相比,碳纳米管显示出每个碳原子的导向平均磁性敏感性显著更高.
- 纳米管的磁性易感性表明,平均带结构类似于石墨的结构.
- 在259K的C60) 富勒里特中观察到磁性易感度的急剧上升 (2.5cgs ppm/mol C60)),与分子定向-排序过渡相吻合.
结论:
- 碳纳米管具有独特的电子特性,反映在它们增强的磁性易感性.
- 在C(60) 富勒里特中观察到的灵敏度跳跃提供了直接证据,表明分子间合作作用影响了分子内电子特性.
- 网格力和分子形状变化可能是订购过程中C(60) 富勒里特的敏感性异常的原因.
相关概念视频
01:31Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
01:26Diamagnetism
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Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
02:42Valence Bond Theory
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01:30Paramagnetism
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03:02Colors and Magnetism
Color in Coordination Complexes
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When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...