Chemistry Reference
In-Depth Information
Fig. 8.2 a STM images of a water molecule and two oxygen atoms on a Cu(110) surface. The
water molecule is located on the atomic row separated by 1.5b
0
from the upper oxygen. The white
dashed lines represent the atomic rows. b The water molecule was brought close to the oxygen by
scanning the area at V
s
= 44 mV. c and d While the appearance of the water molecule does not
significantly change, the water molecule is trapped near the oxygen atom, indicating that it is
weakly interacted with oxygen. All images were obtained at I
t
= 0.5 nA and the bias voltage is
shown in each image. The image size is 41 9 41 Å
2
Fig. 8.3 a Typical images of OH dimers compared with an OH monomer. b One of the dimers is
flipped by a voltage pulse of the STM. The white grid lines and the asterisk represent the lattice
of Cu(110) and the inversion center of the flip. c Another one is also flipped in the same way. All
images were obtained at V
s
= 24 mV and I
t
= 5 nA, and size is 40 9 40 Å
2
is associated with the O-H(D) stretch excitation. It is noted that the vibrational
energy is significantly red-shifted from that of free OH (443 meV [
35
]). The
energy of m(OH) is directly related to the strength of H bond [
36
]. In general,
H-bond formation causes the weakening of covalent nature of O-H bond via a
charge-transfer, eventually giving rise to significant red-shift. Therefore the result
