Chemistry Reference
In-Depth Information
Fig. 6.11
Step anisotropy effect at incomplete surface alloying. Snapshot of a random MC atomic
configuration of 0.1ML Pb/Cu(111) at 300 K and initial substrate terrace width of 16 atomic rows.
The larger alloyed stripe width at step B is a result of the eased atomic relaxation of the terrace
in that direction. The
inset
(
down right
) shows atomic arrangement of A and B steps with feasi-
ble directions for relaxation toward threefold symmetry hollow sites on the substrate level.
Light
gray balls
indicate upper Cu terrace atoms (from Michailov [
4
], Copyright c
2009 The American
Physical Society)
Fig. 6.12
Nanoscale staircase surface pattern formation on vicinal fcc(111) interface. Stable
alloyed stripes followed by pure terrace domains are formed at
L
T
>
3
L
S
and
T
L
≤
T
≤
T
H
.
If the surface intermixing is realized across the single steps of the vicinal terraces, for
L
T
<
L
C
(vicinal surface with narrow terraces) the formation of 2D surface alloy is spread over the entire
interface although
E
ATOM
<
E
DB
DIRECT
mean terrace width distribution
L
T
≤
L
C
could be completely alloyed despite that
the system is outside the energy gap for complete alloying, (
6.3
).
6.5.3 Vacancy-Mediated Diffusion Inside Atomic Terraces
The diffusion slowing down inside the terrace argues for dramatic change in the
elastic strain field toward the terrace center. The equilibrium state of the system
