1 |
< |
\documentclass[journal = jpccck, manuscript = article]{achemso} |
2 |
< |
\setkeys{acs}{usetitle = true} |
1 |
> |
% Version 2.0 July 2014 |
2 |
> |
% |
3 |
> |
% To compile to pdf, run: |
4 |
> |
% latex plos.template |
5 |
> |
% bibtex plos.template |
6 |
> |
% latex plos.template |
7 |
> |
% latex plos.template |
8 |
> |
% dvipdf plos.template |
9 |
> |
% |
10 |
> |
% % % % % % % % % % % % % % % % % % % % % % |
11 |
> |
% |
12 |
> |
% -- IMPORTANT NOTE |
13 |
> |
% |
14 |
> |
% Be advised that this is merely a template |
15 |
> |
% designed to facilitate accurate translation of manuscript content |
16 |
> |
% into our production files. |
17 |
> |
% |
18 |
> |
% This template contains extensive comments intended |
19 |
> |
% to minimize problems and delays during our production |
20 |
> |
% process. Please follow the template |
21 |
> |
% whenever possible. |
22 |
> |
% |
23 |
> |
% % % % % % % % % % % % % % % % % % % % % % % |
24 |
> |
% |
25 |
> |
% Once your paper is accepted for publication and enters production, |
26 |
> |
% PLEASE REMOVE ALL TRACKED CHANGES in this file and leave only |
27 |
> |
% the final text of your manuscript. |
28 |
> |
% |
29 |
> |
% DO NOT ADD EXTRA PACKAGES TO THIS TEMPLATE unless absolutely necessary. |
30 |
> |
% Packages included in this template are intentionally |
31 |
> |
% limited and basic in order to reduce the possibility |
32 |
> |
% of issues during our production process. |
33 |
> |
% |
34 |
> |
% % % % % % % % % % % % % % % % % % % % % % % |
35 |
> |
% |
36 |
> |
% -- FIGURES AND TABLES |
37 |
> |
% |
38 |
> |
% DO NOT INCLUDE GRAPHICS IN YOUR MANUSCRIPT |
39 |
> |
% - Figures should be uploaded separately from your manuscript file. |
40 |
> |
% - Figures generated using LaTeX should be extracted and removed from the PDF before submission. |
41 |
> |
% - Figures containing multiple panels/subfigures must be combined into one image file before submission. |
42 |
> |
% See http://www.plosone.org/static/figureGuidelines for PLOS figure guidelines. |
43 |
> |
% |
44 |
> |
% Tables should be cell-based and may not contain: |
45 |
> |
% - tabs/spacing/line breaks within cells to alter layout |
46 |
> |
% - vertically-merged cells (no tabular environments within tabular environments, do not use \multirow) |
47 |
> |
% - colors, shading, or graphic objects |
48 |
> |
% See http://www.plosone.org/static/figureGuidelines#tables for table guidelines. |
49 |
> |
% |
50 |
> |
% For sideways tables, use the {rotating} package and use \begin{sidewaystable} instead of \begin{table} in the appropriate section. PLOS guidelines do not accomodate sideways figures. |
51 |
> |
% |
52 |
> |
% % % % % % % % % % % % % % % % % % % % % % % % |
53 |
> |
% |
54 |
> |
% -- EQUATIONS, MATH SYMBOLS, SUBSCRIPTS, AND SUPERSCRIPTS |
55 |
> |
% |
56 |
> |
% IMPORTANT |
57 |
> |
% Below are a few tips to help format your equations and other special characters according to our specifications. For more tips to help reduce the possibility of formatting errors during conversion, please see our LaTeX guidelines at http://www.plosone.org/static/latexGuidelines |
58 |
> |
% |
59 |
> |
% Please be sure to include all portions of an equation in the math environment, and for any superscripts or subscripts also include the base number/text. For example, use $mathrm{mm}^2$ instead of mm$^2$ (do not use \textsuperscript command). |
60 |
> |
% |
61 |
> |
% DO NOT USE the \rm command to render mathmode characters in roman font, instead use $\mathrm{}$ |
62 |
> |
% For bolding characters in mathmode, please use $\mathbf{}$ |
63 |
> |
% |
64 |
> |
% Please add line breaks to long equations when possible in order to fit our 2-column layout. |
65 |
> |
% |
66 |
> |
% For inline equations, please do not include punctuation within the math environment unless this is part of the equation. |
67 |
> |
% |
68 |
> |
% For spaces within the math environment please use the \; or \: commands, even within \text{} (do not use smaller spacing as this does not convert well). |
69 |
> |
% |
70 |
> |
% |
71 |
> |
% % % % % % % % % % % % % % % % % % % % % % % % |
72 |
|
|
73 |
< |
\usepackage{caption} |
74 |
< |
\usepackage{geometry} |
75 |
< |
\usepackage{natbib} |
76 |
< |
\usepackage{setspace} |
8 |
< |
\usepackage{xkeyval} |
9 |
< |
%%%%%%%%%%%%%%%%%%%%%%% |
73 |
> |
|
74 |
> |
|
75 |
> |
\documentclass[10pt]{article} |
76 |
> |
% amsmath package, useful for mathematical formulas |
77 |
|
\usepackage{amsmath} |
78 |
+ |
% amssymb package, useful for mathematical symbols |
79 |
|
\usepackage{amssymb} |
80 |
< |
\usepackage{times} |
81 |
< |
\usepackage{mathptm} |
82 |
< |
\usepackage{caption} |
83 |
< |
\usepackage{tabularx} |
84 |
< |
\usepackage{longtable} |
85 |
< |
\usepackage{graphicx} |
86 |
< |
\usepackage{achemso} |
87 |
< |
\usepackage{wrapfig} |
80 |
> |
|
81 |
> |
% cite package, to clean up citations in the main text. Do not remove. |
82 |
> |
\usepackage{cite} |
83 |
> |
|
84 |
> |
\usepackage{hyperref} |
85 |
> |
|
86 |
> |
% line numbers |
87 |
> |
\usepackage{lineno} |
88 |
> |
|
89 |
> |
% ligatures disabled |
90 |
> |
\usepackage{microtype} |
91 |
> |
\DisableLigatures[f]{encoding = *, family = * } |
92 |
> |
|
93 |
> |
% rotating package for sideways tables |
94 |
> |
%\usepackage{rotating} |
95 |
> |
|
96 |
> |
% If you wish to include algorithms, please use one of the packages below. Also, please see the algorithm section of our LaTeX guidelines (http://www.plosone.org/static/latexGuidelines) for important information about required formatting. |
97 |
> |
%\usepackage{algorithmic} |
98 |
> |
%\usepackage{algorithmicx} |
99 |
> |
|
100 |
> |
% Use doublespacing - comment out for single spacing |
101 |
> |
%\usepackage{setspace} |
102 |
> |
%\doublespacing |
103 |
> |
|
104 |
> |
|
105 |
> |
% Text layout |
106 |
> |
\topmargin 0.0cm |
107 |
> |
\oddsidemargin 0.5cm |
108 |
> |
\evensidemargin 0.5cm |
109 |
> |
\textwidth 16cm |
110 |
> |
\textheight 21cm |
111 |
> |
|
112 |
> |
% Bold the 'Figure #' in the caption and separate it with a period |
113 |
> |
% Captions will be left justified |
114 |
> |
\usepackage[labelfont=bf,labelsep=period,justification=raggedright]{caption} |
115 |
|
\usepackage[version=3]{mhchem} % this is a great package for formatting chemical reactions |
116 |
|
\usepackage{url} |
117 |
+ |
\usepackage{graphicx} |
118 |
|
|
119 |
< |
\title{Interfacial Thermal Conductance of Alkanethiolate-Protected Gold |
120 |
< |
Nanospheres} |
119 |
> |
% Use the PLoS provided BiBTeX style |
120 |
> |
\bibliographystyle{plos2009} |
121 |
|
|
122 |
< |
\author{Kelsey M. Stocker} |
123 |
< |
\author{J. Daniel Gezelter} |
124 |
< |
\email{gezelter@nd.edu} |
125 |
< |
\affiliation[University of Notre Dame]{251 Nieuwland Science Hall\\ |
30 |
< |
Department of Chemistry and Biochemistry\\ |
31 |
< |
University of Notre Dame\\ |
32 |
< |
Notre Dame, Indiana 46556} |
122 |
> |
% Remove brackets from numbering in List of References |
123 |
> |
\makeatletter |
124 |
> |
\renewcommand{\@biblabel}[1]{\quad#1.} |
125 |
> |
\makeatother |
126 |
|
|
127 |
|
|
128 |
< |
\keywords{Nanoparticles, interfaces, thermal conductance} |
128 |
> |
% Leave date blank |
129 |
> |
\date{} |
130 |
|
|
131 |
< |
\begin{document} |
131 |
> |
\pagestyle{myheadings} |
132 |
|
|
133 |
< |
\begin{tocentry} |
40 |
< |
\center\includegraphics[width=3.9cm]{figures/TOC} |
41 |
< |
\end{tocentry} |
133 |
> |
%% Include all macros below. Please limit the use of macros. |
134 |
|
|
135 |
< |
\newcolumntype{A}{p{1.5in}} |
44 |
< |
\newcolumntype{B}{p{0.75in}} |
135 |
> |
%% END MACROS SECTION |
136 |
|
|
137 |
|
|
138 |
< |
\begin{abstract} |
138 |
> |
\begin{document} |
139 |
> |
|
140 |
> |
|
141 |
> |
% Title must be 150 characters or less |
142 |
> |
\begin{flushleft} |
143 |
> |
{\Large |
144 |
> |
\textbf{Interfacial Thermal Conductance of Thiolate-Protected |
145 |
> |
Gold Nanospheres} |
146 |
> |
} |
147 |
> |
% Insert Author names, affiliations and corresponding author email. |
148 |
> |
\\ |
149 |
> |
Kelsey M. Stocker, |
150 |
> |
Suzanne Kucera, |
151 |
> |
J. Daniel Gezelter$^{\ast}$ |
152 |
> |
\\ |
153 |
> |
251 Nieuwland Science Hall, Department of Chemistry and Biochemistry |
154 |
> |
University of Notre Dame, Notre Dame, Indiana 46556, USA |
155 |
> |
\\ |
156 |
> |
$\ast$ E-mail: gezelter@nd.edu |
157 |
> |
\end{flushleft} |
158 |
> |
|
159 |
> |
% Please keep the abstract between 250 and 300 words |
160 |
> |
\section*{Abstract} |
161 |
|
Molecular dynamics simulations of alkanethiolate-protected and |
162 |
|
solvated gold nanoparticles were carried out in the presence of a |
163 |
|
non-equilibrium heat flux between the solvent and the core of the |
177 |
|
the surface of the particle into the bulk. This mode of heat |
178 |
|
transfer is reduced by slow solvent escape rates, and this effect was |
179 |
|
observed to lower the interfacial conductance for the longer-chain ligands. |
67 |
– |
\end{abstract} |
180 |
|
|
181 |
< |
\newpage |
181 |
> |
% Please keep the Author Summary between 150 and 200 words |
182 |
> |
% Use first person. PLOS ONE authors please skip this step. |
183 |
> |
% Author Summary not valid for PLOS ONE submissions. |
184 |
> |
%\section*{Author Summary} |
185 |
|
|
186 |
+ |
%\documentclass[journal = jpccck, manuscript = article]{achemso} |
187 |
+ |
%\setkeys{acs}{usetitle = true} |
188 |
+ |
|
189 |
+ |
% \usepackage{caption} |
190 |
+ |
% \usepackage{geometry} |
191 |
+ |
% \usepackage{natbib} |
192 |
+ |
% \usepackage{setspace} |
193 |
+ |
% \usepackage{xkeyval} |
194 |
+ |
% %%%%%%%%%%%%%%%%%%%%%%% |
195 |
+ |
% \usepackage{amsmath} |
196 |
+ |
% \usepackage{amssymb} |
197 |
+ |
% \usepackage{times} |
198 |
+ |
% \usepackage{mathptm} |
199 |
+ |
% \usepackage{caption} |
200 |
+ |
% \usepackage{tabularx} |
201 |
+ |
% \usepackage{longtable} |
202 |
+ |
% \usepackage{graphicx} |
203 |
+ |
% \usepackage{achemso} |
204 |
+ |
% \usepackage{wrapfig} |
205 |
+ |
% |
206 |
+ |
|
207 |
+ |
% \title{Interfacial Thermal Conductance of Alkanethiolate-Protected Gold |
208 |
+ |
% Nanospheres} |
209 |
+ |
|
210 |
+ |
% \author{Kelsey M. Stocker} |
211 |
+ |
% \author{Suzanne Kucera} |
212 |
+ |
% \author{J. Daniel Gezelter} |
213 |
+ |
% \email{gezelter@nd.edu} |
214 |
+ |
% \affiliation[University of Notre Dame]{251 Nieuwland Science Hall\\ |
215 |
+ |
% Department of Chemistry and Biochemistry\\ |
216 |
+ |
% University of Notre Dame\\ |
217 |
+ |
% Notre Dame, Indiana 46556} |
218 |
+ |
|
219 |
+ |
|
220 |
+ |
% \keywords{Nanoparticles, interfaces, thermal conductance} |
221 |
+ |
|
222 |
+ |
% \begin{document} |
223 |
+ |
|
224 |
+ |
% \begin{tocentry} |
225 |
+ |
% \center\includegraphics[width=3.9cm]{figures/TOC} |
226 |
+ |
% \end{tocentry} |
227 |
+ |
|
228 |
+ |
% \newcolumntype{A}{p{1.5in}} |
229 |
+ |
% \newcolumntype{B}{p{0.75in}} |
230 |
+ |
|
231 |
+ |
|
232 |
+ |
% \begin{abstract} |
233 |
+ |
% Molecular dynamics simulations of alkanethiolate-protected and |
234 |
+ |
% solvated gold nanoparticles were carried out in the presence of a |
235 |
+ |
% non-equilibrium heat flux between the solvent and the core of the |
236 |
+ |
% particle. The interfacial thermal conductance ($G$) was computed for |
237 |
+ |
% these interfaces, and the behavior of the thermal conductance was |
238 |
+ |
% studied as a function of particle size and ligand chain length. In |
239 |
+ |
% all cases, thermal conductance of the ligand-protected particles was |
240 |
+ |
% higher than the bare metal--solvent interface. A number of |
241 |
+ |
% mechanisms for the enhanced conductance were investigated, including |
242 |
+ |
% thiolate-driven corrugation of the metal surface, solvent mobility |
243 |
+ |
% and ordering at the interface, and ligand ordering relative to the |
244 |
+ |
% particle surface. The shortest and least flexible ligand, butanethiolate, |
245 |
+ |
% exhibited the highest interfacial thermal conductance and was the |
246 |
+ |
% least likely to trap solvent molecules within the ligand layer. At |
247 |
+ |
% the 50\% coverage levels studied, heat transfer into the solvent |
248 |
+ |
% relies primarily on convective motion of the solvent molecules from |
249 |
+ |
% the surface of the particle into the bulk. This mode of heat |
250 |
+ |
% transfer is reduced by slow solvent escape rates, and this effect was |
251 |
+ |
% observed to lower the interfacial conductance for the longer-chain ligands. |
252 |
+ |
% \end{abstract} |
253 |
+ |
|
254 |
+ |
% \newpage |
255 |
+ |
|
256 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
257 |
|
% INTRODUCTION |
258 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
259 |
< |
\section{Introduction} |
259 |
> |
\section*{Introduction} |
260 |
|
|
261 |
|
Heat transport across various nanostructured interfaces has been |
262 |
|
the subject of intense experimental |
335 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
336 |
|
% STRUCTURE OF SELF-ASSEMBLED MONOLAYERS ON NANOPARTICLES |
337 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
338 |
< |
\subsection{Structures of Self-Assembled Monolayers on Nanoparticles} |
338 |
> |
\subsection*{Structures of Self-Assembled Monolayers on Nanoparticles} |
339 |
|
|
340 |
|
Though the ligand packing on planar surfaces has been characterized for many |
341 |
|
different ligands and surface facets, it is not obvious \emph{a |
375 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
376 |
|
% NON-PERIODIC VSS-RNEMD METHODOLOGY |
377 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
378 |
< |
\subsection{Creating a thermal flux between particles and solvent} |
378 |
> |
\subsection*{Creating a thermal flux between particles and solvent} |
379 |
|
|
380 |
|
The non-periodic variant of VSS-RNEMD\cite{Stocker:2014qq} applies a |
381 |
|
series of velocity scaling and shearing moves at regular intervals to |
420 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
421 |
|
% INTERFACIAL THERMAL CONDUCTANCE |
422 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
423 |
< |
\subsection{Interfacial Thermal Conductance} |
423 |
> |
\subsection*{Interfacial Thermal Conductance} |
424 |
|
|
425 |
|
As described in earlier work,\cite{Stocker:2014qq} the thermal |
426 |
|
conductance of each spherical shell may be defined as the inverse |
445 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
446 |
|
% FORCE FIELDS |
447 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
448 |
< |
\subsection{Force Fields} |
448 |
> |
\subsection*{Force Fields} |
449 |
|
|
450 |
|
Throughout this work, gold -- gold interactions are described by the |
451 |
|
quantum Sutton-Chen (QSC) model.\cite{PhysRevB.59.3527} Previous work\cite{kuang:AuThl} has demonstrated that the electronic contributions to heat conduction (which are missing from the QSC model) across heterogeneous metal / non-metal interfaces are negligible compared to phonon excitation, which is captured by the classical model. The hexane |
469 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
470 |
|
% SIMULATION PROTOCOL |
471 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
472 |
< |
\subsection{Simulation Protocol} |
472 |
> |
\subsection*{Simulation Protocol} |
473 |
|
|
474 |
|
Gold nanospheres with radii ranging from 10 - 25 \AA\ were created |
475 |
|
from a bulk fcc lattice and were thermally equilibrated prior to the |
489 |
|
\ref{fig:NP25_C12h1} shows one of the solvated 25 \AA\ nanoparticles |
490 |
|
passivated with the $C_{12}$ ligands. |
491 |
|
|
307 |
– |
\begin{figure} |
308 |
– |
\includegraphics[width=\linewidth]{figures/NP25_C12h1} |
309 |
– |
\caption{A 25 \AA\ radius gold nanoparticle protected with a |
310 |
– |
half-monolayer of TraPPE-UA dodecanethiolate (C$_{12}$) |
311 |
– |
ligands and solvated in TraPPE-UA hexane. The interfacial |
312 |
– |
thermal conductance is computed by applying a kinetic energy |
313 |
– |
flux between the nanoparticle and an outer shell of |
314 |
– |
solvent.} |
315 |
– |
\label{fig:NP25_C12h1} |
316 |
– |
\end{figure} |
317 |
– |
|
492 |
|
Once equilibrated, thermal fluxes were applied for 1 ns, until stable |
493 |
|
temperature gradients had developed. Systems were run under moderate |
494 |
|
pressure (50 atm) with an average temperature (250K) that maintained a |
526 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
527 |
|
% EFFECT OF PARTICLE SIZE |
528 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
529 |
< |
\section{Results} |
529 |
> |
\section*{Results} |
530 |
|
|
531 |
|
We modeled four sizes of nanoparticles ($R =$ 10, 15, 20, and 25 |
532 |
|
\AA). The smallest particle size produces the lowest interfacial |
555 |
|
increase in the interfacial thermal conductance over the bare |
556 |
|
nanoparticles. |
557 |
|
|
384 |
– |
\begin{figure} |
385 |
– |
\includegraphics[width=\linewidth]{figures/NPthiols_G} |
386 |
– |
\caption{Interfacial thermal conductance ($G$) values for 4 |
387 |
– |
sizes of solvated nanoparticles that are bare or protected |
388 |
– |
with a 50\% coverage of C$_{4}$, C$_{8}$, or C$_{12}$ |
389 |
– |
alkanethiolate ligands.} |
390 |
– |
\label{fig:NPthiols_G} |
391 |
– |
\end{figure} |
392 |
– |
|
558 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
559 |
|
% HEAT TRANSFER MECHANISMS |
560 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
561 |
< |
\section{Mechanisms for Ligand-Enhanced Heat Transfer} |
561 |
> |
%\section*{Discussion} |
562 |
|
|
563 |
|
corrugation |
564 |
|
|
571 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
572 |
|
% CORRUGATION OF PARTICLE SURFACE |
573 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
574 |
< |
\subsection{Corrugation of Particle Surface} |
574 |
> |
\subsection*{Corrugation of Particle Surface} |
575 |
|
|
576 |
|
The bonding sites for thiols on gold surfaces have been studied |
577 |
|
extensively and include configurations beyond the traditional atop, |
632 |
|
extends into the core of the nanoparticle, indicating widespread |
633 |
|
disruption of the lattice. |
634 |
|
|
470 |
– |
\begin{figure} |
471 |
– |
\includegraphics[width=\linewidth]{figures/NP10_fcc} |
472 |
– |
\caption{Fraction of gold atoms with fcc ordering as a |
473 |
– |
function of radius for a 10 \AA\ radius nanoparticle. The |
474 |
– |
decreased fraction of fcc-ordered atoms in ligand-protected |
475 |
– |
nanoparticles relative to bare particles indicates |
476 |
– |
restructuring of the nanoparticle surface by the thiolate |
477 |
– |
sulfur atoms.} |
478 |
– |
\label{fig:Corrugation} |
479 |
– |
\end{figure} |
480 |
– |
|
635 |
|
We may describe the thickness of the disrupted nanoparticle surface by |
636 |
|
defining a corrugation factor, $c$, as the ratio of the radius at |
637 |
|
which the fraction of gold atoms with fcc ordering is 0.9 and the |
668 |
|
|
669 |
|
|
670 |
|
|
517 |
– |
\begin{figure} |
518 |
– |
\includegraphics[width=\linewidth]{figures/NPthiols_combo} |
519 |
– |
\caption{Computed corrugation values, solvent escape rates, |
520 |
– |
ligand orientational $P_2$ values, and interfacial solvent |
521 |
– |
orientational $P_2$ values for 4 sizes of solvated |
522 |
– |
nanoparticles that are bare or protected with a 50\% |
523 |
– |
coverage of C$_{4}$, C$_{8}$, or C$_{12}$ alkanethiolate |
524 |
– |
ligands.} |
525 |
– |
\label{fig:NPthiols_combo} |
526 |
– |
\end{figure} |
671 |
|
|
528 |
– |
|
672 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
673 |
|
% MOBILITY OF INTERFACIAL SOLVENT |
674 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
675 |
< |
\subsection{Mobility of Interfacial Solvent} |
675 |
> |
\subsection*{Mobility of Interfacial Solvent} |
676 |
|
|
677 |
|
Another possible mechanism for increasing interfacial conductance is |
678 |
|
the mobility of the interfacial solvent. We used a survival |
707 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
708 |
|
% ORIENTATION OF LIGAND CHAINS |
709 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
710 |
< |
\subsection{Orientation of Ligand Chains} |
710 |
> |
\subsection*{Orientation of Ligand Chains} |
711 |
|
|
712 |
|
As the ligand chain length increases in length, it exhibits |
713 |
|
significantly more conformational flexibility. Thus, different lengths |
731 |
|
willing to lie down on the nanoparticle surface and exhibit increased |
732 |
|
population at $\cos{(\theta)} = 0$. |
733 |
|
|
591 |
– |
\begin{figure} |
592 |
– |
\includegraphics[width=\linewidth]{figures/NP_pAngle} |
593 |
– |
\caption{The two extreme cases of ligand orientation relative |
594 |
– |
to the nanoparticle surface: the ligand completely |
595 |
– |
outstretched ($\cos{(\theta)} = -1$) and the ligand fully |
596 |
– |
lying down on the particle surface ($\cos{(\theta)} = 0$).} |
597 |
– |
\label{fig:NP_pAngle} |
598 |
– |
\end{figure} |
734 |
|
|
735 |
|
% \begin{figure} |
736 |
|
% \includegraphics[width=\linewidth]{figures/thiol_pAngle} |
755 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
756 |
|
% ORIENTATION OF INTERFACIAL SOLVENT |
757 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
758 |
< |
\subsection{Orientation of Interfacial Solvent} |
758 |
> |
\subsection*{Orientation of Interfacial Solvent} |
759 |
|
|
760 |
|
Similarly, we examined the distribution of \emph{hexane} molecule |
761 |
|
orientations relative to the particle surface using the same angular |
798 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
799 |
|
% SOLVENT PENETRATION OF LIGAND LAYER |
800 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
801 |
< |
\subsection{Solvent Penetration of Ligand Layer} |
801 |
> |
\subsection*{Solvent Penetration of Ligand Layer} |
802 |
|
|
803 |
|
We may also determine the extent of ligand -- solvent interaction by |
804 |
|
calculating the hexane density as a function of radius. Figure |
806 |
|
profiles for a solvated 25 \AA\ radius nanoparticle with no ligands, |
807 |
|
and 50\% coverage of C$_{4}$, C$_{8}$, and C$_{12}$ thiolates. |
808 |
|
|
674 |
– |
\begin{figure} |
675 |
– |
\includegraphics[width=\linewidth]{figures/hex_density} |
676 |
– |
\caption{Radial hexane density profiles for 25 \AA\ radius |
677 |
– |
nanoparticles with no ligands (circles), C$_{4}$ ligands |
678 |
– |
(squares), C$_{8}$ ligands (triangles), and C$_{12}$ ligands |
679 |
– |
(diamonds). As ligand chain length increases, the nearby |
680 |
– |
solvent is excluded from the ligand layer. Some solvent is |
681 |
– |
present inside the particle $r_{max}$ location due to |
682 |
– |
faceting of the nanoparticle surface.} |
683 |
– |
\label{fig:hex_density} |
684 |
– |
\end{figure} |
809 |
|
|
810 |
|
The differences between the radii at which the hexane surrounding the |
811 |
|
ligand-covered particles reaches bulk density correspond nearly |
818 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
819 |
|
% DISCUSSION |
820 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
821 |
< |
\section{Discussion} |
821 |
> |
\section*{Discussion} |
822 |
|
|
823 |
|
The chemical bond between the metal and the ligand introduces |
824 |
|
vibrational overlap that is not present between the bare metal surface |
836 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
837 |
|
% **ACKNOWLEDGMENTS** |
838 |
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
839 |
< |
\begin{acknowledgement} |
839 |
> |
%\begin{acknowledgement} |
840 |
> |
\section*{Acknowledgments} |
841 |
|
Support for this project was provided by the National Science Foundation |
842 |
|
under grant CHE-1362211. Computational time was provided by the |
843 |
|
Center for Research Computing (CRC) at the University of Notre Dame. |
844 |
< |
\end{acknowledgement} |
844 |
> |
%\end{acknowledgement} |
845 |
|
|
846 |
|
|
847 |
< |
\newpage |
847 |
> |
%\section*{References} |
848 |
|
|
849 |
+ |
\newpage |
850 |
|
\bibliography{NPthiols} |
851 |
+ |
\newpage |
852 |
+ |
%\section*{Figure Legends} |
853 |
|
|
854 |
+ |
\begin{figure} |
855 |
+ |
\includegraphics[width=\linewidth]{figures/NP25_C12h1} |
856 |
+ |
\caption{{\bf A 25 \AA\ radius gold nanoparticle protected with a |
857 |
+ |
half-monolayer of TraPPE-UA dodecanethiolate (C$_{12}$) |
858 |
+ |
ligands and solvated in TraPPE-UA hexane.} The interfacial |
859 |
+ |
thermal conductance is computed by applying a kinetic energy |
860 |
+ |
flux between the nanoparticle and an outer shell of |
861 |
+ |
solvent.} |
862 |
+ |
\label{fig:NP25_C12h1} |
863 |
+ |
\end{figure} |
864 |
+ |
|
865 |
+ |
\begin{figure} |
866 |
+ |
\includegraphics[width=\linewidth]{figures/NPthiols_G} |
867 |
+ |
\caption{{\bf Interfacial thermal conductance ($G$) values for 4 |
868 |
+ |
sizes of solvated nanoparticles that are bare or protected |
869 |
+ |
with a 50\% coverage of C$_{4}$, C$_{8}$, or C$_{12}$ |
870 |
+ |
alkanethiolate ligands.}} |
871 |
+ |
\label{fig:NPthiols_G} |
872 |
+ |
\end{figure} |
873 |
+ |
|
874 |
+ |
\begin{figure} |
875 |
+ |
\includegraphics[width=\linewidth]{figures/NP10_fcc} |
876 |
+ |
\caption{{\bf Fraction of gold atoms with fcc ordering as a |
877 |
+ |
function of radius for a 10 \AA\ radius nanoparticle}. The |
878 |
+ |
decreased fraction of fcc-ordered atoms in ligand-protected |
879 |
+ |
nanoparticles relative to bare particles indicates |
880 |
+ |
restructuring of the nanoparticle surface by the thiolate |
881 |
+ |
sulfur atoms.} |
882 |
+ |
\label{fig:Corrugation} |
883 |
+ |
\end{figure} |
884 |
+ |
|
885 |
+ |
\begin{figure} |
886 |
+ |
\includegraphics[width=\linewidth]{figures/NPthiols_combo} |
887 |
+ |
\caption{{\bf Computed corrugation values, solvent escape rates, |
888 |
+ |
ligand orientational $P_2$ values, and interfacial solvent |
889 |
+ |
orientational $P_2$ values for 4 sizes of solvated |
890 |
+ |
nanoparticles that are bare or protected with a 50\% |
891 |
+ |
coverage of C$_{4}$, C$_{8}$, or C$_{12}$ alkanethiolate |
892 |
+ |
ligands.}} |
893 |
+ |
\label{fig:NPthiols_combo} |
894 |
+ |
\end{figure} |
895 |
+ |
|
896 |
+ |
\begin{figure} |
897 |
+ |
\includegraphics[width=\linewidth]{figures/NP_pAngle} |
898 |
+ |
\caption{{\bf The two extreme cases of ligand orientation relative |
899 |
+ |
to the nanoparticle surface: the ligand completely |
900 |
+ |
outstretched ($\cos{(\theta)} = -1$) and the ligand fully |
901 |
+ |
lying down on the particle surface ($\cos{(\theta)} = 0$).}} |
902 |
+ |
\label{fig:NP_pAngle} |
903 |
+ |
\end{figure} |
904 |
+ |
|
905 |
+ |
\begin{figure} |
906 |
+ |
\includegraphics[width=\linewidth]{figures/hex_density} |
907 |
+ |
\caption{{\bf Radial hexane density profiles for 25 \AA\ radius |
908 |
+ |
nanoparticles with no ligands (circles), C$_{4}$ ligands |
909 |
+ |
(squares), C$_{8}$ ligands (triangles), and C$_{12}$ ligands |
910 |
+ |
(diamonds).} As ligand chain length increases, the nearby |
911 |
+ |
solvent is excluded from the ligand layer. Some solvent is |
912 |
+ |
present inside the particle $r_{max}$ location due to |
913 |
+ |
faceting of the nanoparticle surface.} |
914 |
+ |
\label{fig:hex_density} |
915 |
+ |
\end{figure} |
916 |
+ |
|
917 |
|
\end{document} |