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Fig. 7.4 The calculated
structure of hydroxyl group
on Cu(110) from side and top
view. The OH bond length
and the angle between the
axis and the surface normal
are 0.99 Å and 62,
respectively
Fig. 7.5 a STM image
simultaneously acquired for
an OH and OD. b Tunneling
current recorded with the tip
fixed over the one depression
OD at I
t
= 5nAat
V
s
= 24 mV. c Schematic
illustration of the switching
between the two orientations
under the tip. The high-
current (low-current) state is
assigned to the orientations of
OD pointing toward (away
from) the tip
can be ascribed to the reduced lifetime of the vibrational excited states between
OH and OD, since the lower vibrational energy of OD stretch results in a more
efficient decay of the excited state into the ground state, which prevents the
vibrational up-pumping process [
34
].
7.2.2 Structure and Dynamics of a Hydroxyl Group on Cu(110)
The structure of OH on Cu(110) was determined by DFT calculations.
1
The
inclined geometry of the OH axis toward [001] axis is obtained as the optimized
1
DFT calculations were performed using the STATE code [Y. Morikawa et al. Phys. Rev. B 69,
041403 (2004).]. The OH was put on one side of a three-layer Cu slab arrayed in a 2 9 3 surface
unit cell, and the vacuum region of 12.89 Å was inserted between slabs. A GGA-optimized lattice
