Introduction to Nanoscience and Nanotechnology. Chris Binns
Чтение книги онлайн.

Читать онлайн книгу Introduction to Nanoscience and Nanotechnology - Chris Binns страница 16

Название: Introduction to Nanoscience and Nanotechnology

Автор: Chris Binns

Издательство: John Wiley & Sons Limited

Жанр: Отраслевые издания

Серия:

isbn: 9781119172253

isbn:

СКАЧАТЬ very large numbers, the metric system introduces a new prefix every time we multiply or divide the standard units by 1000. Thus, a thousandth of a meter is a milli‐meter or mm (from the Roman word mille meaning 1000); a thousandth of a millimeter (or a millionth of a meter) is a micro‐meter or μm (from the Greek word mikros meaning small). Similarly, a thousandth of a micrometer (or a billionth of a meter) is a nano‐meter or nm (from the Greek word nanos meaning dwarf). As shown in Figure I.1 in the introduction (“The Nanoworld”), we will be dealing with building blocks that vary from 100 nm across down to atoms, which are 0.1–0.4 nm across.

      These days instruments can directly image nanostructures, for example, Figure 1.1 shows a scanning tunneling microscope (STM – see Chapter 5, Section 5.4.1) image of a few manganese nanoparticles with a diameter of about 3 nm deposited onto a bed of carbon‐60 molecules (“bucky balls” – see Chapter 3) with a diameter of 0.7 nm on silicon. It thus displays two different nanoparticles of interest in the same image. This could just as easily be a picture of snowballs on a bed of marbles, and it is easy to lose sight of the difference in scale between our world and that of the nanoparticles. To get some idea of the scale, take a sharp pencil and gently tap it onto a piece of paper with just enough force to get a mark that is barely visible. This will typically be about 100 μm or 100 000 nm across. If the frame in Figure 1.1 were this large, it would contain about 100 000 000 of the Mn nanoparticles and 20 000 000 000 of the carbon‐60 nanoparticles, which is about three times the population of the planet.

image

      Source: Reproduced with the permission of the American Institute of Physics from M. D. Upward et al. [1].

image

      Source: The Universe image is from UCL Mathematical and Physical sciences and reproduced under creative commons 2.0 license. The solar system and atomic nucleus images are reproduced under creative commons 3.0 license.

      Our direct experience in the macroscopic world suggests that matter is continuous and thus with nothing but our eyes for sensors, the original suggestion that matter is made from continuous basic elements such as earth, fire, air, and water seems reasonable. In fact, there are subtle indications of underlying invisible particles of matter, for example, in a dusty room traversed by shafts of sunlight, the dust particles dance around due to the motion of something invisible. Mostly, this is microscopic air currents but the glittering of the smallest particles is due to random collisions from large numbers of individual air molecules and is known as Brownian motion (see Chapter 7, Section 7.2).

image

      Source: Odysses, https://commons.wikimedia.org/wiki/File:Bust_of_an_unknown_Greek_‐_Museo_archeologico_nazionale_di_Napoli.jpg.

      Meanwhile, focusing on atoms, one could argue that the basic philosophy outlined above, which led to their being proposed, means that you should really attribute the a‐tomon to more fundamental constituents of atoms, such as electrons and quarks. There is a good reason to stick with atoms, however, since we are talking about constituents of materials and if we pick on a particular material, say copper, the smallest indivisible unit of “copperness” is the copper atom. If we divide a copper atom in two we get two atoms of different materials.

СКАЧАТЬ