Quantum corral:
Quantum corral: Fe atoms on Cu(111) (r=7.3 nm) Fe atoms on Cu(111) (r=7.3 nm)
Nanoscience is not physics, chemistry, engineering or biology.
Nanoscience is not physics, chemistry, engineering or biology.
It is all of them.
It is all of them.
S.M. Lindsay, Introduction to Nanoscience, Oxford University Press (2009)
Multiwalled Carbon Multiwalled Carbon Nanotubes
Nanotubes
Dendrimers Dendrimers DNA DNA
Imaging Imaging
0.1nm 1nm 10nm 100nm 1m 10 m
bottom-up bottom-up
Organic synthesis Self-assembly
biomolecules nanoclusters
top-down top-down
Photolitography Microprinting
Nanoscience is about the phenomena that occur in systems with Nanoscience is about the phenomena that occur in systems with nanometer dimensions.
nanometer dimensions.
Bohr radius = 0.5292Å ≈ 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: 2.7·1028 C atoms
Typical nanosystems may contain from hundreds to tens of Typical nanosystems may contain from hundreds to tens of thousands of atoms.
thousands of atoms.
Graphite
Graphite: 2.3·103 Kg·m-3 = 1.15·1029 C atoms·m-3
Diamond
Diamond: 3.5·103 Kg·m-3 = 1.76·1029 C atoms·m-3
Nanoscience is where atomic physics converges with the physics Nanoscience is where atomic physics converges with the physics and chemistry of complex systems.
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 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. 0.05 Mole N2
• Mass of earth’s atmosphere is 5 ·1018 kg (80% N2), 1 mole of N2 weights 28 g.
• Moles N2 in atmosphere are ca. 2 ·1020
• Fraction exhaled by Caesar: 0.05/ 2 · 1020 = 2.5 · 10-22: 150 “Caesar Molecules”/mole
• In each breath we breath in: 0.05 ·150 or about 7 molecules
•
1981 Invention of Scanning Tunneling Microscopy 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, 57-61 (1982)
• 1986 – First International Conference on STM
•Santiago de Compostela, Spain, 14-18 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, 930-933 (1986)
• 1986 Invention of Atomic Force Microscopy 1986 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 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 Making materials from atomic layers
Alternate layers of HgTe and HgCdTe
Atomic scale synthesis by “pushing atoms”
Atomic scale synthesis by “pushing atoms”
• “We can arrange atoms the way we want.”
(Courtesy of Prof. Wilson Ho)
STM deposition
Resonant antennas Resonant antennas
for light emission and absorption for light emission and absorption
• “It is possible to emit light from a whole set of antennas.”
Photoactive Photoactive
dendrimers dendrimers
Nanophotonics
Nanophotonics
Spintronics 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
1 2 22E 2mL
Copyright (c) Stuart Lindsay 2008
(Courtesy of Dylan M. Spencer)
Quantum dots
Quantum dots
Fluctuations play a large role in small systems simply because they are relatively larger in smaller systems.Fluctuations scale as N/Nwith respect to the mean energy
But N/N 1 in small systems
• Complexity is a rapidly increasing function of N:
N A
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
