Nanoscience

About nanoscience

The letter ‘nano-’ prefixed to ‘science’ and ‘technology’ became popular after the National Nanotechnology Initiative (NNI) was launched by the United States federal government in 2000. Now the term nanoscience and nanotechnology widely spread and are readily understood. According to Oxford dictionary, nanoscience is defined as “the scientific study of objects that are less than 100 nanometers long” and so is nanotechnology in the same manner, which probably took the definition of nanotechnology made in the 2000’s NNI: “the manipulation of matter with at least one dimension sized from 1 to 100 nanometers”. However, in such disciplines in chemistry as supramolecular chemistry, polymer chemistry, macromolecular chemistry, inorganic catalysis, and electrochemistry, chemists were studying nano-sized molecules and inorganic compounds earlier than a couple of decades before the year of 2000, when modern instruments for imaging at the near atomic level started to be invented. Biologists also have been studying molecules in the living matter that some of them are definitely “less than 100 nanometeres long”. The new physical properties of nano-sized metal crystals had been studied at least for three decades before 2000 in physics and materials science. Nanoscience began much earlier than 2000, and in fact the term nanotechnology first appeared in the 1970s.

Nanoscience, experiencing a millennial renaissance, may have important implications for a top-to-down manipulation of matter instead of the bottom-to-top manipulation, for example in chemistry, of individual molecules into the form of assembly, polymerization, or clustering. The bottom-to-top approach above adds new functionality to the existing one with the same principle as the traditional chemistry, and it does not require the understanding of bulk properties that nanoscience tells itself from and that most industries have relied on. New knowledge of nanoscience from those disciplines in chemistry and biology came from within those disciplines. It may be clearer if we see nanoscience as a new branch of materials science in which bulk matter has traditionally been dealt with but nano-sized matter had not been concerned. Thus, it is important to understand first the properties of bulk solids in order to understand new properties discovered in nanoscience.

This historical perspective on nanoscience may be helpful for new comers to nanoscience and nanotechnology on which subjects they will learn. Remember that nanoscience was born again to public needs. The nanoscale materials are the most promising one to meet such public needs as water sustainability, energy, health, environment, and industries for future generations including nanoelectronics and future computing. People from different science and engineering disciplines need to work together on those public issues. Some people create nanomaterials from atoms or molecules or from bulk materials. Some study the novel properties of nanomaterials, and some make devices with nanomaterials. Nanoscience is of necessity interdisciplinary.

As the size of matter reduces to the nanometer range, the property of the surface becomes crucial to the property of the new matter. Some properties are dominated by the surface. Thus, it is also important to understand the properties of the surface of nano-sized matter.

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Surfaces and interfaces

Surface and interface is an important subject not only in academic research but also in industry. Most tools, equipment, electronic devices and vehicle parts made from metals need to be coated properly for longer and robust use against corrosion so that direct contact with air and water can be prevented. Thus, industry demands practical techniques in coating. Surface tension of liquid, two-dimensional pressure, is also crucial to the industries producing cleaning, chemical, pharmaceutical, cosmetic products and many others that liquid is dealt with in the manufacturing processes. Those industrial technologies are mostly at the macroscopic level.

In academia, research about surface has been done to understand some sort of mechanism or chemical and physical properties at the atomic and molecular level. Things important in surface science include surface lattice vibrations, surface potentials and electronic structure at a surface, adsorption and desorption of molecules, interfaces of gas-solid or liquid-solid surface, and crystallographic structure of a surface layer at the atomic level. Surfaces of interest are typically those of metal oxides and transition metals.

One of the popular disciplines in surface science is heterogeneous catalysis: chemical reactions catalyzed at solid surfaces. This discipline has been important to petroleum refineries and chemical industries although it did not often provide valuable insight in practice. Nonetheless, the chemical and physical studies around heterogeneous catalysis have led to the growth of surface science. Along with surface science, research on heterogeneous catalysis also concerns how fast and energetically effective and chemically selective a catalytic reaction is, preparation of catalysts, and photocatalysis on metals at a metal-oxide support for catalysts dispersion and reactivity, and microporous solids such as zeolites.

Semiconductor device physics along with the development of ultrahigh vacuum contributed the development of instrumentation for surface science studies. By using electrons, photons, ions, electric fields, or heat as a source of excitation, surfaces with or without foreign species can be characterized at the atomic and molecular level. Regarding molecules adsorbed on a surface, however, there is no surface-specific instrument available until now except scanning tunneling microscopy for a monolayer of molecules at an atomically clean surface. Conventional vibrational spectroscopies and solid-state nuclear magnetic resonance have been adapted to characterize molecules at solid surfaces.

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References and some books useful to understand surface science

Encyclopedia-like

For interfacial properties

• Intermolecular and Surface Forces by Jacob N. Israelachvili, 3rd edition, Elsevier, 2011

For optical properties

• Optical properties of metal clusters by Uwe Kreibig and Michael Vollmer, Springer, 1995
• Optical properties of solids by Mark Fox, 2nd edition, Oxford University Press, 2010
• Optical waves in crystals by Amnon Yariv and Pochi Yeh, Wiley, 1984

For magnetic properties

• Magnetism and magnetic materials by J. M. D. Coey, Cambridge University Press, 2010
• Magnetism in condensed matter by Stephen Blundell, Oxford University Press, 2001

For surface physics

• Physics at surfaces by Andrew Zangwill, Cambridge University Press, 1988
• The surface science of metal oxides by V. E. Henrich and P. A. Cox, Cambridge University Press, 1994
• Semiconductor surfaces and interfaces by Winfried Mönch, 3rd edition, Springer, 2001
• The chemical physics of surfaces by S. Roy Morrison, 2nd edition, Plenum Press, 1990
• Photoelectron spectroscopy by Stefan Hüfner, 3rd edition, Springer, 2003

For surface chemistry and catalysis

• Introduction to surface chemistry and catalysis by Gabor A. Somorjai and Yimin Li, 2nd edition, Wiley, 2010
• Principles and practice of heterogeneous catalysis by J. M. Thomas and ‎W. J. Thomas, VCH, 1997
• Heterogeneous catalysis in industrial practice by Charles N. Satterfield, 2nd edition, McGraw-Hill, 1991
• Heterogeneous catalysis: principles and applications by G. C. Bond, 2nd edition, Oxford University Press, 1987

For characterization

• Modern techniques of surface science by D. Phil Woodruff, 3rd edition, Cambridge University Press, 2016
• Low energy electrons and surface chemistry by G. Ertl and J. Küppers, 2nd edition, VCH, 1985
• Surface analytical techniques by J. C. Rivière, Oxford University Press, 1990
• Vibrational spectroscopy of molecules on surface edited by John T. Yates, Jr. and Theodore E. Madey, Plenum Press, 1997
• Spectroscopic characterization of heterogeneous catalysts, Part B: chemisorption of probe molecules edited by J. L. G. Fierro, Elsevier, 1990 (Chapter 4. NMR of adsorbed molecules used as probes for surface investigation)