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metallic atoms and the solvent, the effective viscosity is a |
49 |
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essentially a free parameter that must be tuned to give experimentally |
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relevant simulations. |
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< |
|
51 |
> |
\begin{figure}[htbp] |
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\centering |
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\includegraphics[width=\linewidth]{images/stochbound.pdf} |
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\caption{Methodology for nanoparticle cooling. Equations of motion for metal atoms contained in the outer 4 {\AA} were determined by Langevins' Equations of motion. Metal atoms outside this region were allowed to evolve under Newtonian dynamics.} |
55 |
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\label{fig:langevinSketch} |
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\end{figure} |
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The viscosity ($\eta$) can be tuned by comparing the cooling rate that |
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a set of nanoparticles experience with the known cooling rates for |
59 |
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those particles obtained via the laser heating experiments. |
103 |
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Values for the interfacial conductance have been determined by a |
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number of groups for similar nanoparticles and range from a low |
105 |
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$87.5\times 10^{6}$ $(\mathrm{Wm^{-2}K^{-1}})$ to $120\times 10^{6}$ |
106 |
< |
$(\mathrm{Wm^{-2}K^{-1}})$.\cite{XXX} |
106 |
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$(\mathrm{Wm^{-2}K^{-1}})$.\cite{hartlandPrv2007} Plech {\it et al.} reported a value for the interfacial conductance of $G=105\pm 15$ $(\mathrm{Wm^{-2}K^{-1}})$ and |
107 |
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$G=130\pm 15$ $(\mathrm{Wm^{-2}K^{-1}})$ for Pt nanoparticles.\cite{plech:195423,PhysRevB.66.224301} |
108 |
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|
109 |
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We conducted our simulations at both ends of the range of |
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experimentally-determined values for the interfacial conductance. |
116 |
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$(\mathrm{Wm^{-2}K^{-1}})$ was used. Based on calculations we have |
117 |
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done using raw data from the Hartland group's thermal half-time |
118 |
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experiments on Au nanospheres, we believe that the true G values are |
119 |
< |
closer to the faster regime: $117\times 10^{6}$ |
114 |
< |
$(\mathrm{Wm^{-2}K^{-1}})$. |
119 |
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closer to the faster regime: $117\times 10^{6}$ $(\mathrm{Wm^{-2}K^{-1}})$. |
120 |
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|
121 |
+ |
|
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The rate of cooling for the nanoparticles in a molecular dynamics |
123 |
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simulation can then be tuned by changing the effective solvent |
124 |
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viscosity ($\eta$) until the nanoparticle cooling rate matches the |