Page 17 - Science at the nanoscale

RPS: PSP0007 - Science-at-Nanoscale
15:10
June 9, 2009
1.2. The Nanoscale
In summary, the key events in the short history of modern
nanotechnology may be described as follows: The vision of
nanotechnology was first popularised by Feynman in 1959, when
he outlined the prospects for atomic-scale engineering. In 1981,
Binnig and Rohrer invented the scanning tunneling microscopy,
which enabled scientists to “see” and manipulate atoms for the
first time. Corresponding advancements in supramolecular chem-
istry, particularly the discovery of the buckminsterfullerenes (or
buckyballs) by Curl, Kroto and Smalley gave scientists a whole
class of nanoscale building blocks with which to construct a whole
range of nanostructures.
THE NANOSCALE
1.2
To start off our discussion on the nanoscale, we first refer to the
metric system. The following table gives a summary of the metric
system.
Sometimes it is difficult to appreciate the smallness of the
nanoscale. It is thus useful to relate the size scale to items that
we commonly find in our home. For example, imagine you take
a single strand of human hair. The cross section of a human hair
is circular in shape (let us assume to be 100 µm in diametre), and
imagine you have a very sharp knife. Use the knife to slice the
cross section of the human hair into 100 slices with equal width.
After which take out one of the 100 slices and use yet another
sharp knife to cut the cross section of that single slice into 1000
slices, again with uniform width. If one takes out one of the 1000
slices, the width of the single strip is equal to 1 nanometre!!! The
above hypothetical process is illustrated in Fig. 1.4. This is an 7 ch01
extremely small size scale and yet there are lots of fascinating phe-
nomena for us to discover.
If one poses a question, how small is a nanometre? Here are
some interesting answers:
(1) the diametre of the C 60 buckyball molecule
(2) half as wide as a DNA molecule
(3) 2 times the diametre of a Rubidium atom
(4) 10 times the diametre of a Hydrogen atom
(5) the de Broglie wavelength of an electron with an energy of
1.5eV