Chemistry Reference
In-Depth Information
Fig. 9.4 a STM images for a
water molecule and an OH
group located on the same
atomic row of Cu(110)
(dashed line). b A water-OH
complex produced by
dragging the water molecule
to the OH group along the
atomic row. c Schematic
illustration of the reaction.
d The complex superimposed
with the lattice of the
substrate. e The counterpart
of d. The complex can be
flipped between d and e state
by a voltage pulse of the
STM. The images were
acquired at V
s
= 24 mV and
I
t
= 0.5 nA and the image
size is 47 9 22 Å
2
for a and
b, and 15 9 14 Å
2
for d and
e
Fig. 9.5 Sequential STM images of a water-hydroxyl complex formation a-b, flipping b-d and
dissociation c-d. The grid lines represent the lattice of Cu(110) and the yellow stars represent the
O position of hydroxyl. e A typical current trace measured over the complex. The STM tip was
fixed at the height corresponding to V
s
= 24 mV and I
t
= 0.5 nA during the measurement. The
rapid flipping gives a wide feature in the high current state compared to the low current state. The
abrupt drops of the current indicate the moment of the dissociation. In this case the complex is
dissociated at the first current drop, and reformed the H bond at the abrupt increase of the current)
When a water molecule is reacted with a hydroxyl group locating on a
neighboring row of the water, a different complex can be obtained (Figs.
9.6
a-b).
The product is characterized by an oval-shaped protrusion (label this product as
[001]-complex) and the asterisk in Fig.
9.6
b indicates the original position of the
