Chemistry Reference
In-Depth Information
excess coverage. On the other hand, the spot positions due to the (223) facet struc-
ture remain fixed, i.e., the additional coverage and the associated additional elec-
tron density do not change the terrace structure of the (223) surface orientation. An
example is shown in the top part of Fig.
9.7
. Here the splitting is 5.3% SBZ for 1.35
1.35ML
10
6
Δ
k
(223)
=21.3%SBZ
10
5
Δ
k
deco
=
5.3%SBZ
10
4
-25 -20 -15 -10 -5 0 5 10 15
k
|| [1 1 2]
(%SBZ)
Fig. 9.7
Top
: Exemplary line scan in LEED taken along the [112
direction for a Pb coverage
of 1.35 ML together with fits of new satellite peaks (see text). Pb layers were adsorbed at 75 K
substrate temperature.
Bottom
: Plot of reciprocal lattice vectors of the satellite peaks versus the Pb
excess coverage
]
(relative to 1.31 ML). The solid (
blue
) curves represent the Fermi wave vector
k
F
,
1D
of a 1D electron gas induced by the Pb excess coverage assuming a valence state of 2. The
coincidence of 2
k
F
(
dashed-dotted (red) line
) with the lattice vectors of the superlattice results in
nesting
δ
