Nanoscience

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Nanoscience
Shared by: Pete Roht
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posted:
9/13/2008
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What IS Nanoscience?

When people talk about Nanoscience, they start by describing things

Physicists and Material Scientists point to things like new nanocarbon materials: They effuse about nanocarbon’s strength and electrical properties



Graphene Carbon Nanotube



C60 Buckminster Fullerene

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Biologists counter that nanocarbon is only a recent discovery

THEY’VE been studying DNA and RNA for much longer

(And are already using it to transform our world)



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Chemists respond: THEY’VE been synthesizing molecules for over a century! Waves How do you figure out an electron’s wavelength?



electron = h / p



“De Broglie’s Relationship”



( = electron wavelength, h = Planck’s Constant, p = electron’s momentum)



This relationship was based on series of experiments late 1800’s / early 1900’s To put the size of an electron’s wavelength in perspective:



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Size of Things

Millimeters Ball of a ball point pen Thickness of paper Human hair Talcum Powder Fiberglass fibers Carbon fiber Human red blood cell E-coli virus Wavelength of visible light Size of a modern transistor Size of Smallpox virus 0.5 0.1 0.02 - 0.2



(orange = man-made things)

Microns Nanometers



100 20 – 200 40 10 5 4–6 1 0.35 – 0.75 0.25 0.2 – 0.3



350 – 750 250 200 – 300



Electron wavelength: Upper limit ~ 10 nm Diameter of Carbon Nanotube Diameter of DNA spiral Diameter of C60 Buckyball Diameter of Benzene ring Size of one Atom



3 2 0.7 0.7 0.1



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Below that line = Nanoscience!

It’s NOT just about the metric units we prefer to use when measuring things

Things above that line are still often measured using nanometers



It IS about the SCIENCE (QM) => Electrons are mushy clouds of size ~ De Broglie Above that line, clouds seem small: Electrons ~ hard B-B like dots Below that line, mushy cloudiness of electrons becomes very important

Controls electrical, optical, mechanical and other properties Controls bonding and nanostructure



The Science Changes! Microscience ≠ Nanoscience

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Or putting it into more human terms Above that line:

It is still the sensible world of Sir Isaac Newton (and his physical laws) It is still the world WE commonly experience Even though we DO need microscopes to see its smaller things And even if those smaller things seem unduly influenced by:



Water tension, static charge . . . (things we largely ignore)



Below that line:

The rules of Quantum Mechanics => Mushy electron waves take over



And our (Newtonian) instincts and assumptions are frequently dead wrong!



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



LIGHT WAVES Separate NanoTECHNOLOGY form MicroTECHNOLOGY

Technology = The things we make and how we make them As opposed to the underlying science dictating how they act

Where does light’s wavelength enter into technology?

Micro technology is based on the use of light Earliest was the use of PHOTOENGRAVING: Use of shrunken light images to pattern metal parts =>



Micro projection of light images =



Way we make the billions of transistors in the integrated circuits of our PCs, iPods . . .



(a.k.a. “Microfabrication”)

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



But HOW does Light Wavelength affect Technology?

Micro-photoengraving (photolithography) confines projected light to small beams

Can “confine” by focusing light with a lens Can “confine” by passing light through holes / shadow masks



But you cannot confine a wave into a beam narrower than its wavelength



Shadow images of water waves, from left, passing thru gap in barrier



Explore fully in lecture 2 - For now, point is can’t photo-process below wavelength



Consequences?

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Size of Things

Millimeters Ball of a ball point pen Thickness of paper Human hair Talcum Powder Fiberglass fibers Carbon fiber Human red blood cell E-coli virus Visible Light Wavelength: 0.5 0.1 0.02 - 0.2



(orange = man-made things)

Microns Nanometers



100 20 – 200 40 10 5 4–6 1 0.35 – 0.75 microns



1000 350 – 750 nm



Size of a modern transistor Size of Smallpox virus



0.25 0.2 – 0.3



250 200 – 300



Electron wavelength: Upper upper limit ~ 10 nm Diameter of Carbon Nanotube Diameter of DNA spiral Diameter of C60 Buckyball Diameter of Benzene ring Size of one Atom



3 2 0.7 0.7 0.1



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Above the new (upper) line:

We can still use light-based “Microfabrication” techniques And even though they were developed for electronics,



they are now also applied to making all sorts of micro things!



Below that new line:

NO longer able to use Microfabrication Replacement = “Nanofabrication” or “Nanotechnology” But don’t yet really know what that replacement will be! Why Nanoscience research is now such a mix of different techniques Recurring theme: Hope we can get nano things to ASSEMBLE THEMSELVES (!!!)



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



To recap:

There IS a fundamental change in SCIENCE below about 10 nanometers:

Newton is out the window. Quantum Mechanics is in. Hard sensible objects are replaced by squishy electron waves / clouds Intuition, based on our life experience => fundamentally flawed



There IS a fundamental change in TECHNOLOGY below 100 nanometers:

Light will not focus this small Light image based fabrication ceases to work Need something new (Nanotechnology) - Still being defined!!!



So it is NOT just when THINGS happen to be measured in units of nanometers

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Uniqueness + Weirdness led us to subtitle this class: "We're not in Kansas anymore!"

This was intended to recall Dorothy's chagrin when the familiar and comfortable experiences of her native Kansas were replaced by the strangeness of Oz



This was NOT intended to disparage Kansas

(As I was compelled to explain when I received a telephone call from the office of the junior U.S. Senator from Kansas questioning my use of this subtitle in the National Science Foundation proposal that led to this class)



But this class should induce in you disorientation similar to Dorothy's:

Because, paraphrasing Neils Bohr:



"Anyone who does not have a headache after their first encounter with quantum mechanics clearly has not understood a thing!"



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



And so where are we going in this class?

A common theme is wavelength, so:

Class 2) We will start by studying waves Of ALL types - including nice friendly water waves and light waves:



Class 3) We'll then tackle our squirreliest topic: Electron waves & quantum mechanics

But we'll do this mostly based on what we learned about water waves + some history of why scientists became convinced electrons were truly wavelike



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



We’ll then talk about technology

Class 4) We’ll learn a bit about microfabrication & microelectronics



RF



But the lesson will be why, despite MOORE'S LAW, these cannot be extrapolated to nano sizes



Class 5) With that knowledge, we’ll distinguish nano science from nano technology





There is a LOT of good Nanoscience, but not yet much in the way of viable Nanotechnology!

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



We'll then discuss Microfabrication's likely replacement: Nanoscale Self-Assembly

Class 6) Early forms of self-assembly that man tamed (such as crystal growth)



Leading us to the master of self-assembly: Mother Nature

Or what a billion years of random experimentation produced, including:

Classes 7 & 8) Self-assembly of organic molecules. Class 9) The incredible processes of DNA



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



From that foundation, we’ll then discuss:

Class 10) How you see and measure at the nanoscale



Class 11) How this might all come together producing entirely new nano devices

This will include descriptions and possible visits to some of our own UVA nano research labs



(i.e. what is going on in our basements that you probably don't know about but should know about - and could get involved with!)



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



And finally to put nanoscience and nanotechnology in perspective we'll discuss:

Class 12) The science fiction of nanoscience and nanotechnology



Class 13) Versus the legitimate fears and challenges of nanoscience & nanotechnology



"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Labs?

- Waves ("slinky" and "snakey" springs) - Water Waves - Microfabrication



- Scanning Electron Microscope

- An introduction to the scanning tunneling microscope (STM) and Atomic Force Microscope - Using STM to see individual atoms on the surface of graphite



- Using the AFM to measure micro samples such as CDs and DVDs

- AFM of near-nanoscale integrated circuit test chips for Micron Technologies - AFM or STM of X, where X = Nanotubes, C60 Buckminster Fullerene, Atomic steps on the surface of gold, Islands of Ge on Si, Etched and fractured surfaces of crystals . . . - Quantum Dot Size vs. Color - Charlottesville CSI (DNA Fingerprinting)

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Homework?

- Do-it-yourself models of graphene, nanotubes and Buckyballs - Do-it-yourself models of DNA - Study of "UVA Virtual Lab" virtual reality recreations of our Scanning electron microscope Scanning tunneling microscope Atomic force microscope - Chapters from textbook - Excerpts from Nano science fiction including Michael Crichton's novel "Prey" - Newspapers and magazine articles on concerns raised about nanotechnology - Readings you identify on favorite topics / concerns

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience



Credits / Acknowledgements

Funding for this class was obtained from the National Science Foundation (under their Nanoscience Undergraduate Education program) and from the University of Virginia. At the University of Virginia, the class development team is led by John C. Bean and Keith Williams (who serve as principal class instructors in alternating semesters), with input from Lloyd Harriott, Avik Ghosh and Nathan Swami. This set of notes was authored by John C. Bean who also created all figures not explicitly credited above (with the exception of lecture preview figures which are credited in their home set of lecture notes). Many of those figures (and much of the material to be used for this class) are drawn from the "UVA Virtual Lab" (www.virlab.virginia.edu) website developed under earlier NSF grants.



Copyright John C. Bean (2008)

(However, permission is granted for use by individual instructors in non-profit academic institutions)

"We're not in Kansas Anymore!" - A Hands-on Introduction to Nanoscience




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