Quantum corral: Fe atoms on Cu(111) (r=7.3 nm)

Nanoscience is not physics, chemistry, engineering or biology. It is all of them. S.M. Lindsay, Introduction to Nanoscience, Oxford University Press (2009) Multiwalled Carbon Nanotubes Dendrimers DNA Imaging

0.1nm 1nm 10nm 100nm 1  m 10  m bottom-up Organic synthesis Self-assembly biomolecules nanoclusters top-down Photolitography Microprinting Nanoscience is about the phenomena that occur in systems with nanometer dimensions.

Bohr radius = Å ≈ 0.05 nm C atom (VdW radius)=0.17 nm In a 1nm line: 3 C atoms In a 1nm·1nm surface: 9 C atoms In a 1nm·1nm·1nm cube: 27 C atoms In a 1m·1m·1m cube: 2.7·10 28 C atoms Typical nanosystems may contain from hundreds to tens of thousands of atoms.

Graphite Graphite: 2.3·10 3 Kg·m -3 = 1.15·10 29 C atoms·m -3 Diamond Diamond: 3.5·10 3 Kg·m -3 = 1.76·10 29 C atoms·m -3

Nanoscience is where atomic physics converges with the physics and chemistry of complex systems. Quantum Mechanics Statistical Mechanics Quantum Mechanics dominates the world of atoms, but typical nanosystems may contain from hundreds to tens of thousands atoms. Emergent behavior How much a system is quantum mechanical?

1. Below a certain length scale (that depends on interaction strengths) systems must be described using quantum mechanics. Ex. quantum dots, nanocatalysts, electronic transport through nanowires amd thin films 2. Many processes depend on the number of available energy states per unit energy. This quantity varies with the dimensionality of the system. 3. The effective concentration of reactants that are confined in nanostructures may be very high.

1 mole at STP occupies 22.4L, one breath is ca Mole N 2 Mass of earth’s atmosphere is 5 ·10 18 kg (80% N 2 ), 1 mole of N 2 weights 28 g. Moles N 2 in atmosphere are ca. 2 ·10 20 Fraction exhaled by Caesar: 0.05/ 2 · = 2.5 · : 150 “Caesar Molecules”/mole In each breath we breath in: 0.05 ·150 or about 7 molecules

1981 Invention of Scanning Tunneling Microscopy

G. Binning, H. Rohrer, C. Berger and E. Weibel Surface studies by Scanning Tunneling Microscopy, Phys. Rev. Lett. 49, (1982) 1986 – First International Conference on STM Santiago de Compostela, Spain, July 1986 – Nobel Prize to G. Binning and H. Rohrer 1988 – STM Imaging of DNA and biological structures

G. Binning, C.F. Quate and C. Berger Atomic Force Microscopy, Phys. Rev. Lett. 56, (1986) 1986 Invention of Atomic Force Microscopy1986 Invention of Atomic Force Microscopy

Talk given to the American Physical Society, 1959

“We can reverse the lens of an electron microscope in order to demagnify as well as magnify……This, when you demagnify it 25,000x, it is still 80Å in diameter – 32 atoms across.” Fresnel Lens made by EBL for focusing X-rays (submicron patterning) Current e-beam technology allows features as small as 10 nm to be written. C. David, Paul Scherrer Institut

“We would just have to press the same metal plate again into the plastic and we would have another copy.” PDMS Stamp technology Copyright (c) Stuart Lindsay 2008

“A source of ions, sent through the lens in reverse, could be focused to a very small spot.” (Courtesy of FEI Inc.) FIB = Focused Ion Beam

Molecular structure by direct imaging “The wavelength of an electron is only 1/20 of an Å. So it should be possible to see the individual atoms.” Cryo-EM reconstruction of the Ribosome (LeBarron et al., 2008) 20 nm

“Consider the possibility that we too can make a thing very small, which does what we want – that we can manufacture an object that maneuvers at that level! …… Consider any machine – for example, an automobile- and ask about the problems of making an infinitesimal machine like it.” World’s smallest motor (Zettl Lab) (Courtesy of Professor Alex Zettl)

“So, you simply evaporate until you have a block of stuff which has the elements…… What could we do with layered materials with just the right layers?” T. Aoki, M. Takeguchi, P. Boieriu, R. Singh, C. Grein, Y. Chang, S. Sivananthan and D. J. Smith, Microstructural characterization of HgTe/HgCdTe superlattices J. Cryst, Growth, 2004, 271, 29-36, Making materials from atomic layers Alternate layers of HgTe and HgCdTe

Atomic scale synthesis by “pushing atoms” “We can arrange atoms the way we want.” (Courtesy of Prof. Wilson Ho) STM deposition

Resonant antennas for light emission and absorption “It is possible to emit light from a whole set of antennas.” Photoactivedendrimers Nanophotonics

Spintronics “We could use, not just circuits, but some systems involving quantized energy levels, or the interaction of quantized spins.” Electron spin valves have become the dominant readout device in the disk drives.

Particle in a box Copyright (c) Stuart Lindsay 2008 (Courtesy of Dylan M. Spencer) Quantum dots

 Fluctuations play a large role in small systems simply because they are relatively larger in smaller systems. Fluctuations scale as  N/N  with respect to the mean energy But  N/N   1 in small systems Complexity is a rapidly increasing function of N:

Adequate complexity and fluctuation. The critical size scale where fluctuations are big enough and the system is complex enough is indeed the nanoscale. Copyright (c) Stuart Lindsay 2008