碳纳米管可能成为一种磁屏障
2010-4-3 纳米应用前沿 Tags:
【纳米科技世界论坛快讯】Understanding and controlling the magnetic properties of carbon-based materials is crucial for employing these structures in future nano- and bioscience applications. Using carbon-13 nuclear magnetic resonance spectroscopy, researchers in Europe and the US have now discovered that the inner cavities of doped carbon nanotubes show the largest diamagnetic shielding of any carbon material. The result means that the nanotubes might be useful as magnetic shields in nanoelectronic devices and in nanobiomedicine for imaging and sensing.
When a magnetic field is applied to a material, the electrons surrounding the nucleus start to circulate in a direction that is perpendicular to this field. This generates a secondary magnetic field known as the induced magnetic field, which opposes the applied magnetic field around the region of the nucleus. The nucleus thus experiences a weaker magnetic field (called the effective magnetic field) and is said to be "shielded" diamagnetically.
Large diamagnetic shielding
Christophe Goze-Bac from the CNRS at University of Montpellier and colleagues in Sweden, Spain and the US now report on the largest diamagnetic shielding ever observed in carbon allotropes. The effects the researchers observe are robust, increase as the applied magnetic field increases and do not depend on temperature.
The results, which were obtained using high-resolution solid-state nuclear magnetic resonance (NMR) techniques, show that the largest obtainable diamagnetic shielding is not inside a doped C60 ball, as previously thought, but inside doped carbon nanotubes. Moreover, this shielding can be controlled externally by doping and functionalizing CNTs.
"These 'peapod' nanomaterials could thus be potentially valuable as nanomagnetic shields in nanoelectronic and nanobiomedical engineering applications," Goze-Bac told nanotechweb.org. Such shielding would protect medical implants from high-frequency radiation, for example.
Goze-Bac added that another important application could be to interface nanotubes with living cells and track them at the nanoscale by measuring the diamagnetic fields by NMR.
The team now plans to continue investigating these nanomaterials and develop NMR spectroscopy and imaging in vivo.
The work was reported in J. Chem. Phys. 132 021102 doi:10.1063/1.3284740
原文作者：Belle Dumé 来源：nanotechweb.org
编辑显示在:科技爱好与博览 http://www.naf.com.cn更多文章请点击.
When a magnetic field is applied to a material, the electrons surrounding the nucleus start to circulate in a direction that is perpendicular to this field. This generates a secondary magnetic field known as the induced magnetic field, which opposes the applied magnetic field around the region of the nucleus. The nucleus thus experiences a weaker magnetic field (called the effective magnetic field) and is said to be "shielded" diamagnetically.
Large diamagnetic shielding
Christophe Goze-Bac from the CNRS at University of Montpellier and colleagues in Sweden, Spain and the US now report on the largest diamagnetic shielding ever observed in carbon allotropes. The effects the researchers observe are robust, increase as the applied magnetic field increases and do not depend on temperature.
The results, which were obtained using high-resolution solid-state nuclear magnetic resonance (NMR) techniques, show that the largest obtainable diamagnetic shielding is not inside a doped C60 ball, as previously thought, but inside doped carbon nanotubes. Moreover, this shielding can be controlled externally by doping and functionalizing CNTs.
"These 'peapod' nanomaterials could thus be potentially valuable as nanomagnetic shields in nanoelectronic and nanobiomedical engineering applications," Goze-Bac told nanotechweb.org. Such shielding would protect medical implants from high-frequency radiation, for example.
Goze-Bac added that another important application could be to interface nanotubes with living cells and track them at the nanoscale by measuring the diamagnetic fields by NMR.
The team now plans to continue investigating these nanomaterials and develop NMR spectroscopy and imaging in vivo.
The work was reported in J. Chem. Phys. 132 021102 doi:10.1063/1.3284740
原文作者：Belle Dumé 来源：nanotechweb.org
编辑显示在:科技爱好与博览 http://www.naf.com.cn更多文章请点击.
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