16.2 VLEED Capacity and Reliability
323
Energy (eV)
0
(a.u.)
-2.5
-3.5
7.5
10.0
12.5
15.0
STS feature
Δ z 0
z
*a
*b
Fig. 16.4 The optimal z 0 (E) profiles were read as input by the calculation codes to conduct the
sensitivity examination. Spectrum *a corresponds to the surface that is more fully developed than
spectrum *b. The valley near 7.5 eV correspond to the nonbonding lone pair states as detected using
STS. The violent features below 12.5 eV arise from Bragg diffraction. (Reprinted with permission
from [8, 9])
(4) Geometry-sensitivity examination indicates that the reaction processes are dominated by the formation of the Cu 3 O 2 bond while the SPB, as a subsequence of
bonding, varies insignificantly with the tiny change in bond geometry.
16.2.3 Sensitivity to the SPB
Instead of the three constants (V 0 , δ, γ) and one variable (z 0 ) in current SPB
parametrization, eight independent SPB parameters were used as did in convention to
examine the spectral sensitivity to the SPB. The δ (in ImV(E)) was not considered as
it determines the slope of the ImV(E) and its value depends on the calibration of the
spectral intensity. The corresponding variations of the SPB parameters in Figs. 16.6
and 16.7 are varied by 10% rather than simply by an absolute amount. This is because
most of the parameters, such as λ, z 1 and α, are no constants and thus it would be
meaningful to change them in the equal percentage for comparison purpose. β and η
are introduced as such to modulate the spatial decay of damping at different regions:
ImV(z, E) =
⎧
⎨
⎩
β × ImV (E, z), z ≤ z 1
η × ImV (E, z), z 1 < z < z SL
ImV (E, z), z SL < z
where z SL is the position of the second atomic plane. The z-axis directs into the
crystal.
323
Energy (eV)
0
(a.u.)
-2.5
-3.5
7.5
10.0
12.5
15.0
STS feature
Δ z 0
z
*a
*b
Fig. 16.4 The optimal z 0 (E) profiles were read as input by the calculation codes to conduct the
sensitivity examination. Spectrum *a corresponds to the surface that is more fully developed than
spectrum *b. The valley near 7.5 eV correspond to the nonbonding lone pair states as detected using
STS. The violent features below 12.5 eV arise from Bragg diffraction. (Reprinted with permission
from [8, 9])
(4) Geometry-sensitivity examination indicates that the reaction processes are dominated by the formation of the Cu 3 O 2 bond while the SPB, as a subsequence of
bonding, varies insignificantly with the tiny change in bond geometry.
16.2.3 Sensitivity to the SPB
Instead of the three constants (V 0 , δ, γ) and one variable (z 0 ) in current SPB
parametrization, eight independent SPB parameters were used as did in convention to
examine the spectral sensitivity to the SPB. The δ (in ImV(E)) was not considered as
it determines the slope of the ImV(E) and its value depends on the calibration of the
spectral intensity. The corresponding variations of the SPB parameters in Figs. 16.6
and 16.7 are varied by 10% rather than simply by an absolute amount. This is because
most of the parameters, such as λ, z 1 and α, are no constants and thus it would be
meaningful to change them in the equal percentage for comparison purpose. β and η
are introduced as such to modulate the spatial decay of damping at different regions:
ImV(z, E) =
⎧
⎨
⎩
β × ImV (E, z), z ≤ z 1
η × ImV (E, z), z 1 < z < z SL
ImV (E, z), z SL < z
where z SL is the position of the second atomic plane. The z-axis directs into the
crystal.