11
1.2 sCale, struCture, aNd Behavior
As discussed in the previous section, nano stands for nanometer, one
billionth (10
−9
) of a meter. This defines a length scale that is, for
these materials, important in some way, influencing their mechanical, thermal, electrical, magnetic, optical, and aesthetic properties.
Before embarking on a discussion of these, it is useful to have an
idea of where nano lies in the broader scale of things.
If you ask: What is the smallest particle in matter? Most people
would reply: an atom. Atoms have a diameter of about one tenth of
a nanometer. Atoms are themselves made up of units that can sometimes be thought of as particles: electrons, neutrons, and protons.
They are much smaller, about 10
−15 meters (a femtometer) in diameter, but when things get this small quantum-mechanical effects
make them fuzzy, their size ill defined, so we shall stop there. What
is the other extreme? It used to be of global scale (“the ends of the
Earth,” “poles apart”), but space exploration has changed all that,
enlarging the concept of scale to intergalactic dimensions: light-years,
just under 10,000,000 million km (10
16 meters, 10 pentameters).
Figure 1.11 shows this wide range, from a femtometer at the bottom
to 100 light-years on the top. Its utility is much like that of the time
scale used by geologists in classifying rocks (5 billion years ago to
the present) or of archeologists in charting human history (500,000
BC to 2000 AD): It is a ladder on which things can be hung. Start at
the human scale. It is the one from which perception expands, one
that is built into our language. At the lower end, the diameter of a
hair (“it missed by a hair’s breadth”). The inch, originally the ell,
is the length of the lower joint of the thumb. The foot is, well, the
foot. A yard is a pace. A furlong is the length of a furrow, a league
(about 5 km) is the distance a man or a horse can walk in an hour;
thus 7-league boots take you a day’s journey at one step. Perhaps
that is why these are called Imperial units. You would not design
anything using units like these (although NASA apparently still
does). It was France, a nation that has contributed so much to
rational thinking, that gave us a system with some sense in it. The
National Assembly of the First Republic, by decree in 1790, created
the standards of length, volume, and weight that we know today as
the metric system.
The original proposal was that the meter should be some fraction
of the circumference of the Earth at the equator, but this was not
seen as sufficiently Gallic. The decisive vote went for a fraction of
the length of the meridian that passes through Paris and both poles.
The meter, then, is one ten millionth (10
−7 ) of the length of the
Scale, Structure, and Behavior
1.2 sCale, struCture, aNd Behavior
As discussed in the previous section, nano stands for nanometer, one
billionth (10
−9
) of a meter. This defines a length scale that is, for
these materials, important in some way, influencing their mechanical, thermal, electrical, magnetic, optical, and aesthetic properties.
Before embarking on a discussion of these, it is useful to have an
idea of where nano lies in the broader scale of things.
If you ask: What is the smallest particle in matter? Most people
would reply: an atom. Atoms have a diameter of about one tenth of
a nanometer. Atoms are themselves made up of units that can sometimes be thought of as particles: electrons, neutrons, and protons.
They are much smaller, about 10
−15 meters (a femtometer) in diameter, but when things get this small quantum-mechanical effects
make them fuzzy, their size ill defined, so we shall stop there. What
is the other extreme? It used to be of global scale (“the ends of the
Earth,” “poles apart”), but space exploration has changed all that,
enlarging the concept of scale to intergalactic dimensions: light-years,
just under 10,000,000 million km (10
16 meters, 10 pentameters).
Figure 1.11 shows this wide range, from a femtometer at the bottom
to 100 light-years on the top. Its utility is much like that of the time
scale used by geologists in classifying rocks (5 billion years ago to
the present) or of archeologists in charting human history (500,000
BC to 2000 AD): It is a ladder on which things can be hung. Start at
the human scale. It is the one from which perception expands, one
that is built into our language. At the lower end, the diameter of a
hair (“it missed by a hair’s breadth”). The inch, originally the ell,
is the length of the lower joint of the thumb. The foot is, well, the
foot. A yard is a pace. A furlong is the length of a furrow, a league
(about 5 km) is the distance a man or a horse can walk in an hour;
thus 7-league boots take you a day’s journey at one step. Perhaps
that is why these are called Imperial units. You would not design
anything using units like these (although NASA apparently still
does). It was France, a nation that has contributed so much to
rational thinking, that gave us a system with some sense in it. The
National Assembly of the First Republic, by decree in 1790, created
the standards of length, volume, and weight that we know today as
the metric system.
The original proposal was that the meter should be some fraction
of the circumference of the Earth at the equator, but this was not
seen as sufficiently Gallic. The decisive vote went for a fraction of
the length of the meridian that passes through Paris and both poles.
The meter, then, is one ten millionth (10
−7 ) of the length of the
Scale, Structure, and Behavior