Chemistry Reference
In-Depth Information
Fig. 1.2 a STM image of 2-D ice film formed on Pd(111) at 100 K (175 9 135 Å
2
). b Zoom-in
image of the lace structure (41 9 53 Å
2
). c Zoom-in image of the rosette structure (20 9 20 Å
2
).
Reprinted with permission from Ref. [
69
]. Copyright 2004, American Physical Society
stable. The characterization of individual molecules and small clusters is extre-
mely difficult by means of conventional spectroscopy. STM opens up a novel way
to investigate the structure and dynamics of water molecules on metal surfaces at
the single molecule level. STM studies also provided visible insights to 2-D
wetting layers [
69
]. Figures
1.2
show the STM images of ice layer formed on
Pd(111) at 100 K where the ice-like hexagonal pattern is clearly resolved. Along
with the development of the STM techniques, large-scale computations have been
also developed to examine the adsorption structure of water in the last decade
[
86
-
92
]. Since it is quite difficult to determine the molecular orientations solely by
STM experiments, the calculations based on the density functional theory have
been generally employed to quantitatively interpret STM images. Both STM
experiments and theoretical calculations found that a water molecule adsorbs at a
top site on metal surfaces. Calculations also predicted the water monomer binding
energy increases in order of Au \ Ag \ Cu \ Pd \ Pt \ Ru \ Rh.
1.3 Single Atom/Molecule Science
Characterization of single atoms and molecules has been a scientifically attractive
and challenging subject. Probing individual atoms and molecules makes it possible
to unveil fundamental properties which are hidden behind an ensemble of atoms
and molecules. The important transition of the field of single atom/molecule
science was provided by the invention of STM [
93
] and its derivatives, namely
scanning probe microscope (SPM).
Feynman pointed out ''There's plenty of room at the Bottom'' in his talk on
29th, December in 1959 at the annual meeting of the American Physical Society at
California Institute of Technology [
94
], which is often regarded as the begging of
nanotechnology. He believed in plenty of room for the findings of new phenomena
and the development of bland-new devices working at the atomic scale. Over the
last few decades the research field of nanoscience and nanotechnology has
