--- trunk/nanoglass/experimental.tex 2007/09/27 18:45:55 3233 +++ trunk/nanoglass/experimental.tex 2007/10/04 21:11:58 3247 @@ -63,13 +63,14 @@ that must be tuned to give experimentally relevant sim that must be tuned to give experimentally relevant simulations. \begin{figure}[htbp] \centering -\includegraphics[width=\linewidth]{images/stochbound.pdf} +\includegraphics[width=5in]{images/stochbound.pdf} \caption{Methodology used to mimic the experimental cooling conditions of a hot nanoparticle surrounded by a solvent. Atoms in the core of the particle evolved under Newtonian dynamics, while atoms that were in the outer skin of the particle evolved under Langevin dynamics. -The radial cutoff between the two dynamical regions was set to 4 {\AA} -smaller than the original radius of the liquid droplet.} +The radius of the spherical region operating under Newtonian dynamics, +$r_\textrm{Newton}$ was set to be 4 {\AA} smaller than the original +radius ($R$) of the liquid droplet.} \label{fig:langevinSketch} \end{figure} @@ -145,13 +146,15 @@ cooling rate described by the heat-transfer equations simulation can then be tuned by changing the effective solvent viscosity ($\eta$) until the nanoparticle cooling rate matches the cooling rate described by the heat-transfer equations -(\ref{eq:heateqn}). The effective solvent viscosity (in poise) for a G -of $87.5\times 10^{6}$ $(\mathrm{Wm^{-2}K^{-1}})$ is 0.17, 0.20, and -0.22 for 20 {\AA}, 30 {\AA}, and 40 {\AA} particles, respectively. The -effective solvent viscosity (again in poise) for an interfacial -conductance of $117\times 10^{6}$ $(\mathrm{Wm^{-2}K^{-1}})$ is 0.23, -0.29, and 0.30 for 20 {\AA}, 30 {\AA} and 40 {\AA} particles. Cooling -traces for each particle size are presented in +(\ref{eq:heateqn}). The effective solvent viscosity (in Pa s) for a G +of $87.5\times 10^{6}$ $(\mathrm{Wm^{-2}K^{-1}})$ is $4.2 \times +10^{-6}$, $5.0 \times 10^{-6}$, and +$5.5 \times 10^{-6}$ for 20 {\AA}, 30 {\AA}, and 40 {\AA} particles, respectively. The +effective solvent viscosity (again in Pa s) for an interfacial +conductance of $117\times 10^{6}$ $(\mathrm{Wm^{-2}K^{-1}})$ is $5.7 +\times 10^{-6}$, $7.2 \times 10^{-6}$, and $7.5 \times 10^{-6}$ +for 20 {\AA}, 30 {\AA} and 40 {\AA} particles. Cooling traces for +each particle size are presented in Fig. \ref{fig:images_cooling_plot}. It should be noted that the Langevin thermostat produces cooling curves that are consistent with Newtonian (single-exponential) cooling, which cannot match the cooling @@ -167,17 +170,15 @@ nanoparticles. \begin{figure}[htbp] \centering -\includegraphics[width=\linewidth]{images/cooling_plot.pdf} +\includegraphics[width=5in]{images/cooling_plot.pdf} \caption{Thermal cooling curves obtained from the inverse Laplace transform heat model in Eq. \ref{eq:laplacetransform} (solid line) as well as from molecular dynamics simulations (circles). Effective -solvent viscosities of 0.23-0.30 poise (depending on the radius of the -particle) give the best fit to the experimental cooling curves. -%Since -%this viscosity is substantially in excess of the viscosity of liquid -%water, much of the thermal transfer to the surroundings is probably -%due to the capping agent. -} +solvent viscosities of 4.2-7.5 $\times 10^{-6}$ Pa s (depending on the +radius of the particle) give the best fit to the experimental cooling +curves. This viscosity suggests that the nanoparticles in these +experiments are surrounded by a vapor layer (which is a reasonable +assumptions given the initial temperatures of the particles). } \label{fig:images_cooling_plot} \end{figure} @@ -256,10 +257,10 @@ structural features associated with bulk glass formati \begin{figure}[htbp] \centering -\includegraphics[width=\linewidth]{images/cross_section_array.jpg} +\includegraphics[width=5in]{images/cross_section_array.jpg} \caption{Cutaway views of 30 \AA\ Ag-Cu nanoparticle structures for random alloy (top) and Cu (core) / Ag (shell) initial conditions (bottom). Shown from left to right are the crystalline, liquid droplet, and final glassy bead configurations.} -\label{fig:q6} +\label{fig:cross_sections} \end{figure}