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Nanoparticle manipulation by thermal gradient.

Wei N, Wang HQ, Zheng JC - Nanoscale Res Lett (2012)

Bottom Line: We created a one-dimensional potential valley by imposing a symmetrical thermal gradient inside the nanotube.When the temperature gradient was large enough, the fullerene sank into the valley and became trapped.Compared to nanomanipulation using a scanning tunneling microscope or an atomic force microscope, our method for nanomanipulation has a great advantage by not requiring a direct contact between the probe and the object.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, 361005, China. hqwang@xmu.edu.cn.

ABSTRACT
A method was proposed to manipulate nanoparticles through a thermal gradient. The motion of a fullerene molecule enclosed inside a (10, 10) carbon nanotube with a thermal gradient was studied by molecular dynamics simulations. We created a one-dimensional potential valley by imposing a symmetrical thermal gradient inside the nanotube. When the temperature gradient was large enough, the fullerene sank into the valley and became trapped. The escaping velocities of the fullerene were evaluated based on the relationship between thermal gradient and thermophoretic force. We then introduced a new way to manipulate the position of nanoparticles by translating the position of thermostats with desirable thermal gradients. Compared to nanomanipulation using a scanning tunneling microscope or an atomic force microscope, our method for nanomanipulation has a great advantage by not requiring a direct contact between the probe and the object.

No MeSH data available.


Trapping time of C60 as a function of carbon isotopes (in atomic mass). The unit of time is nanoseconds, and the unit of carbon isotopes is atomic mass.
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Figure 5: Trapping time of C60 as a function of carbon isotopes (in atomic mass). The unit of time is nanoseconds, and the unit of carbon isotopes is atomic mass.

Mentions: The restraining of encapsulated molecular clusters with different masses by the thermal gradient is also considered by replacing carbon atoms in the C60 cluster with various kinds of carbon isotopes. Here, the C60 cluster is employed as a typical case of molecular cluster enclosed into CNT, and the C60 clusters with different masses are applicable for the similar cases of molecules with various masses. According to the equation of the escaping velocity (Equation 7), both mass and velocity of the molecule play an important role in the molecule's escape from the thermal gradient potential valley. In order to further elucidate the relationship of the trapping time and the mass of molecular cluster, C60 clusters consisted of different carbon isotopes, namely 8C, 10C, 14C, and 16C, are considered, and the results are shown in Figure 5. Generally, the C60 cluster can be trapped by thermal gradient induced by a heat flux of 6.5 eV/ps, and the trapping time is in the region of 1.5 to 2.0 ns for the cases of 8C, 10C, 12C, and 14C while less than 1.0 ns for the case of 16C. We then plotted their velocity profiles from the simulations in Figure 6 to examine whether they are coupled with the mass of C60. We can see that the larger the mass of the C60 cluster, the smaller the velocity. For example, compared with the C60 clusters consisted of 8C, 10C, 12C, or 14C, the thermophoretic force induces a much smaller velocity for the 16C60 cluster. Its maximum velocity is about 300 nm/ns, and its velocities after being trapped are reduced to about 100 nm/ns. This explains why it is easier to trap. We can also see that in the same conditions, it does not necessarily take longer for the heavier clusters to be trapped than the lighter ones if their initial velocities are induced by thermal fluctuation [33]. Nevertheless, for the clusters with the same velocities, it will be harder to trap the heavier clusters according to our escaping relationship.


Nanoparticle manipulation by thermal gradient.

Wei N, Wang HQ, Zheng JC - Nanoscale Res Lett (2012)

Trapping time of C60 as a function of carbon isotopes (in atomic mass). The unit of time is nanoseconds, and the unit of carbon isotopes is atomic mass.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3306267&req=5

Figure 5: Trapping time of C60 as a function of carbon isotopes (in atomic mass). The unit of time is nanoseconds, and the unit of carbon isotopes is atomic mass.
Mentions: The restraining of encapsulated molecular clusters with different masses by the thermal gradient is also considered by replacing carbon atoms in the C60 cluster with various kinds of carbon isotopes. Here, the C60 cluster is employed as a typical case of molecular cluster enclosed into CNT, and the C60 clusters with different masses are applicable for the similar cases of molecules with various masses. According to the equation of the escaping velocity (Equation 7), both mass and velocity of the molecule play an important role in the molecule's escape from the thermal gradient potential valley. In order to further elucidate the relationship of the trapping time and the mass of molecular cluster, C60 clusters consisted of different carbon isotopes, namely 8C, 10C, 14C, and 16C, are considered, and the results are shown in Figure 5. Generally, the C60 cluster can be trapped by thermal gradient induced by a heat flux of 6.5 eV/ps, and the trapping time is in the region of 1.5 to 2.0 ns for the cases of 8C, 10C, 12C, and 14C while less than 1.0 ns for the case of 16C. We then plotted their velocity profiles from the simulations in Figure 6 to examine whether they are coupled with the mass of C60. We can see that the larger the mass of the C60 cluster, the smaller the velocity. For example, compared with the C60 clusters consisted of 8C, 10C, 12C, or 14C, the thermophoretic force induces a much smaller velocity for the 16C60 cluster. Its maximum velocity is about 300 nm/ns, and its velocities after being trapped are reduced to about 100 nm/ns. This explains why it is easier to trap. We can also see that in the same conditions, it does not necessarily take longer for the heavier clusters to be trapped than the lighter ones if their initial velocities are induced by thermal fluctuation [33]. Nevertheless, for the clusters with the same velocities, it will be harder to trap the heavier clusters according to our escaping relationship.

Bottom Line: We created a one-dimensional potential valley by imposing a symmetrical thermal gradient inside the nanotube.When the temperature gradient was large enough, the fullerene sank into the valley and became trapped.Compared to nanomanipulation using a scanning tunneling microscope or an atomic force microscope, our method for nanomanipulation has a great advantage by not requiring a direct contact between the probe and the object.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, 361005, China. hqwang@xmu.edu.cn.

ABSTRACT
A method was proposed to manipulate nanoparticles through a thermal gradient. The motion of a fullerene molecule enclosed inside a (10, 10) carbon nanotube with a thermal gradient was studied by molecular dynamics simulations. We created a one-dimensional potential valley by imposing a symmetrical thermal gradient inside the nanotube. When the temperature gradient was large enough, the fullerene sank into the valley and became trapped. The escaping velocities of the fullerene were evaluated based on the relationship between thermal gradient and thermophoretic force. We then introduced a new way to manipulate the position of nanoparticles by translating the position of thermostats with desirable thermal gradients. Compared to nanomanipulation using a scanning tunneling microscope or an atomic force microscope, our method for nanomanipulation has a great advantage by not requiring a direct contact between the probe and the object.

No MeSH data available.