| 392 |
|
% time scale, formation, breakage |
| 393 |
|
\section{Results} |
| 394 |
|
\subsection{Structural remodeling} |
| 395 |
+ |
\subsubsection{Step wandering} |
| 396 |
+ |
\subsubsection{Double layers} |
| 397 |
|
Tao et al. have shown experimentally that the Pt(557) surface |
| 398 |
|
undergoes two separate reconstructions upon CO |
| 399 |
|
adsorption.\cite{Tao:2010} The first involves a doubling of |
| 474 |
|
from the diffusion perpendicular to these edges. Parallel and perpendicular |
| 475 |
|
diffusion constants are shown in Figure \ref{fig:diff}. |
| 476 |
|
|
| 477 |
< |
\subsubsection{Double layer formation dynamics} |
| 477 |
> |
\subsubsection{Dynamics of double layer formation} |
| 478 |
|
The increased amounts of diffusion on Pt at the higher CO coverages plays a primary role in the formation of the double layers observed on Pt. However, this is not a complete explanation as seen by the 33\% Pt system which has higher diffusion constants but did not show any signs of undergoing the doubling. This difference will be explored more fully in the discussion. On the 50\% Pt system, three separate layers were formed over the extended run time of this system. Previous experimental work has given some insight into the upper bounds of the time required for step coalescing.\cite{Williams:1991,Pearl} In this system, as seen in Figure \ref{fig:reconstruct}, the first appearance of a double layer, a nodal site, appears at 19 ns into the simulation. Within 12 ns, nearly half of the step has formed the double layer and by 86 ns, the complete layer has been smoothed. The double layer could be considered ``complete" by 37 ns but is a bit rough or wavy. From the appearance of the first node to the first observed double layer, ignoring roughening, the process took $\sim$20 ns. Another $\sim$40 ns was necessary for the layer to completely straighten. The other two layers in this simulation form over a period of 22 ns and 42 ns respectively. Comparing this to the upper bounds of the image scan, it is likely that aspects of this reconstruction occur very quickly. A possible explanation for this rapid reconstruction is the elevated temperatures our systems were run at. It is likely that the process would take longer at lower temperatures and is an area of exploration for future work. |
| 479 |
|
|
| 480 |
|
%Evolution of surface |
