The scale and spin of life in the little league


May 18, 2007

What is "small"? Chad Mirkin, in the inaugural editorial essay of the journal Small , first published in January 2005, defines nanoscience and technology as a field that focuses on: 1) the development of synthetic methods and surface analytical tools for building structures and materials, typically on the sub-100 nanometer (sic, disregarding the European preference for the French spelling) scale; 2) the identification of the chemical and physical consequences of miniaturisation; 3) the use of such properties in the development of novel and functional materials and devices.

This is not inconsistent with the definitions in the report published jointly by the Royal Society and the Royal Academy of Engineering in July 2004, which defined nanoscience as the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, where properties differ significantly from those at a larger scale, and which defined nanotechnologies as the design, characterisation, production and application of structures, devices and systems by controlling shape and size at nanometre scale.

A definition in terms of size is in line with a forthcoming European definition of nanotechnology that will restrict the term to structures whose scale is less than 100nm in at least two dimensions, thus excluding devices such as quantum wells grown by molecular beam epitaxy. But you are still faced with a situation similar to that of Moli re's Le Bourgeois Gentilhomme ; when Monsieur Jourdain's tutor explains to him what prose is, he exclaims: "Well, what do you know about that! These forty years now, I've been speaking in prose without knowing it! How grateful am I to you for teaching me that!"

Many chemists have been working at sub-100nm scales since much more than 40 years ago without calling it nanotechnology. Mirkin tries to get round this: "Chemists are really 'angstrom-technologists', not nanotechnologists." But four pages later, in news from the micro-nano world, is the headline, "Sub-Angstrom Imaging of a Crystal Lattice". Surely this articulates the nano key breakthrough of the past 25 years or so: we have learnt to manipulate individual atoms and molecules and at almost the same time to see what we have done.

This became popular through scanning probe microscopy, but individual atoms can also be imaged by field ion microscopy and transmission electron microscopy. To this should be added astonishing advances in modelling the structural and electronic properties of nanomaterials.

A functional definition sheds a different light on the meaning of small, in terms of the question, "How is small different from big?" Volume scales as size cubed, whereas surface scales as size squared, so as you get smaller, surface effects become more significant relative to bulk effects. Thus adhesion may dominate over stiffness, and still more over inertial and gravitational forces. A higher proportion of atoms will be surface atoms.

Many of the papers in the journal reflect how small is different from big in such ways. If there is an aspect that is missing, it is the emergence of quantum properties as things get small. As electrons and quasiparticles become spatially confined in small objects, so discrete quantum states appear. At their simplest, these give energy levels that are seen, for example, in the colour of colloidal quantum dots.

In the rapidly growing field of quantum nanoscience and quantum nanotechnology, these properties are extended to more exotic quantum phenomena such as superposition and coherence, and even to non-locality and entanglement. Such phenomena can also be observed in nanoscale superconducting devices and in the spins of isolated electrons in nanostructures. It remains to be seen whether Small will be able to attract papers in the quantum small.

Small seeks to differentiate itself from rival publications Nano Letters (impact factor 9.847), which it sees as having a bent towards chemistry, and from Nanotechnology (whose impact factor rose by 50 per cent last year to 3.322), which Small 's editors characterise as emphasising engineering advances - though the editors of those journals might not necessarily agree. It remains to be seen how Small will compare with them for impact.

Speed of publication is only modest. Papers in the May 2006 issue were received between June and December 2005, corresponding to delays considerably greater than the time it took for news of Galileo's observation of the moons of Jupiter to reach London by horseback in the 16th century. Many nano results are first read on the arXiv website (for which the UK mirror is A student working in my laboratory last summer submitted a paper to an Elsevier journal on July 18, received and responded to referees' comments by August 7, and saw it published online on September 11. On the same day he submitted a revised second paper that was published online on October 17. He cannot understand why all publishers do not work this quickly.

The hard copy of Small is a joy to browse. The table of contents carries an image from each paper and a summary of three sentences or so. After you have skipped the advertisements, there are two pages of highlights from other journals, including rivals such as Nano Letters and Nanotechnology , and two more from sister Wiley-VCH journals. Unlike other journals that send you online for many of the colour figures to save money, colour seems standard throughout. There are sections designated highlights, reviews, communications and full papers, followed by book reviews, an index by keywords and trailers for forthcoming articles.

Small has got off to a splendid start with some excellent papers that reflect the intrinsically interdisciplinary nature of the field. Those searching for papers on a given nano topic will soon find, if they have not already done so, key papers appearing in this journal. And those who can get their hands on the monthly hard copy are in for a good read around the world of the small.

Andrew Briggs is professor of nanomaterials, Oxford University.


Editor - Peter Gölitz and Esther Levy
Publisher - Wiley-VCH. Published monthly since January 2005
Price - €1,760.15 institutions €211.86 individuals
ISSN - 1613 6810 Online ISSN 1613 6829

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