Embed Size (px)
Citation preview
FRONTIERS IN PHYSICS: Lecture 1The Nanoworld – Where Size is Everything...
Philip Moriarty, B403 School of Physics & [email protected]
Just what is nanoscience?
Manipulating atoms, molecules, and electrons
Frontiers in Physics – module overview, structure, and assessment
An artificial periodic table
OUTLINE
FRONTIERS IN PHYSICS – An Overview
The Frontiers in Physics module has been designed to:
(i) Introduce you to the option strands in the School’s physics courses
and, perhaps more importantly,
(ii) Give you an insight into some of the key cutting edge areas of 21st century physics and astronomy.Interwoven themes (but not
restricted to these)2. Astronomy
Lecturer: Frazer Pearce, B103, Centre for Astronomy and Particle Theory
3. Medical Physics
Lecturer: Richard Bowtell, MR13(Magnetic Resonance Centre) and C130
1. Nanoscience
Lecturer: Philip Moriarty, B403, [email protected].
Please e-mail me to organise an appointment.
FRONTIERS IN PHYSICS – An Overview
Website
FRONTIERS IN PHYSICS – An Overview
Moodle + www.youtube.com/Moriarty2112 + Wordpress (To be announced…soon…I promise).
• There isn’t a dedicated textbook to cover the Frontiers material. (This is largely because one of our aims is to introduce you to exciting new “off the press” science). e-book in preparation for Nano component of module.
•Sets of lecture notes availble via Moodle. Powerpoint slides also available.
•We will, however, refer you to the relevant sections in Knight and, equally importantly, give references to websites and to books in the library. Use the library!
Textbook
Assessment• 20% coursework; 80% examination
• Coursework (CW) sets for Semester 1•CW Set 3 – 16 Oct. (Hand-in: 23 Oct.)•CW Set 5 – 30 Oct. (Hand-in: 06 Nov.)•CW Set 7 – 13 Nov. (20 Nov.)•CW Set 9 – 27 Nov. (04 Dec.)
• 500 word scientific article (after Christmas holiday – hand in on Jan. 24)
• Exam: standard first year format. Four questions from six. Each question worth 25 marks. If you answer more than four questions, all will be marked and the best four marks taken.
Exam paper “walk-throughs”
Watching videos is not education. The learner needs to do at least as much work as the teacher to grasp the concepts.
My job in these lectures is primarily to enthuse you and get you interested in the material.
A lot of your learning will happen outside of B1.
Rant of the day
http://physicsfocus.org/philip-moriarty-perform-or-perish-guilty-confessions-of-a-youtube-physicist/
Peer Instruction
Will try Mazur’s Peer Instruction scheme in some Frontiers lectures…
Just what is nanoscience?
• Let’s first consider the nanometre unit.
• A useful “pop. science” estimate is that 1 nm is ~ the length the average person’s hair grows in one second.
•It is, of course, 10-9 m but what does this represent in terms of physical quantities and structures with which you’re more familiar?
Which of the following is closest to the wavelength of red light?
A. B. C. D. E.
2% 5%
84%
4%5%
A. 0.6 nm
B. 6 nm
C. 60 nm
D. 600 nm
E. 6,000 nm
Which of the following is closest to the size of a human red blood cell?
A. B. C. D. E.
19%
4%3%
29%
46%A. 50,000 nmB. 5000 nmC. 50 nmD. 5 nmE. 0.5 nm
The diameter of a gold atom is approximately:
A. B. C. D.
6%
29%
38%
27%
A. 3 nm
B. 0.3 nm
C. 0.03 nm
D. 0.003 nm
The wavelength of an electron (mass = 10-30 kg) travelling at 106 ms-1 is approximately:
A. B. C. D. E.
15%
10%8%
26%
40%
A. 0.01 nm
B. 0.6 nm
C. 20 nm
D. 300 nm
E. 2112 nm
Just what is nanoscience?•Sometimes nanoscience is defined as the study of phenomena, structures, and materials “at the nanometre level”
•This is a nebulous/ “woolly” definition.
1D
Den
sity
of S
tate
sN
(E)
E
• Wikipedia, for example, states “Generally nanotechnology deals with structures 100 nanometers or smaller, and involves developing materials or devices within that size.” [Aside: Be careful when quoting Wikipedia – use additional sources to check Wikipedia’s statements]. Admission: I’ve also been guilty of using this type of definition in the past!
• But why 100 nm? Why not 110 nm or 512 nm or 5 nm...?
Just what is nanoscience?: Size-dependent properties•Much better to focus on
modification of properties than on arbitrary size limits.
•Cross-over from microscopic to nanoscopic regime can be ill-defined (depends on the system).
•Good “rule of thumb”: An optical microscope cannot resolve the detail of nanoscale structures, devices, or systems.
•The key concept behind much of nanoscience is that simply by changing the size of an object, we change its physical, chemical (and biological) properties.
An artificial periodic table: designer materials
www.periodictable.com
•Instead of building materials from different elements, control properties by changing size/shape of nanoparticles...
“A nugget of purest green...”
•But gold isn’t always coloured gold...
• Au nanoparticles (diameter 2 – 10 nm) are red in colour
•Simply by changing nanoparticle size (for certain materials), entire visible spectrumcan be covered.
From Blackadder II, Episode 4 – “Money”
© BBC (1986)
sitemason.vanderbilt.edu/files/ioOfKM/cdse4.jpg
Reaching the atomic limit...•How far can we take this? Can we manipulate matter at the atomic level?
Images from Eigler et al., IBM Almaden; IBM Zurich; and Stefan Tautz, International University Bremen.
•Use scanning probe microscopes (Lectures 4 and 5) to control not only individual atoms but single bonds.
Flipping atomic dominoes
But I am not afraid to consider the final question as to whether, ultimately---in the great future---we can arrange the atoms the way we want; the very atoms, all the way down!
RP Feynman, “There’s Plenty of Room at the Bottom”, 1959
The origin of nanotech.
How many atoms are there in 1 cm3 of a solid?
1 2 3 4
1%
11%
77%
11%
1. ~ 108
2. ~ 1012
3. ~ 1022
4. ~ 1040
But I am not afraid to consider the final question as to whether, ultimately---in the great future---we can arrange the atoms the way we want; the very atoms, all the way down!
RP Feynman, “There’s Plenty of Room at the Bottom”, 1959
The origin of nanotech.
Let’s say atoms are spaced by 4 Å (=0.4 nm). [This can be measured directly using X-ray diffraction or – as we’ll see – a scanning tunnelling microscope]
Why is nanotech. so important?
0.4 nm
In the solid, there is 1 atom per 0.4 x 0.4 x 0.4 nm3
So, 1 atom per 0.064 nm3 There are 1/0.064 atoms per nm3
This is, on average, ~ 16 atoms per nm3
How many nm3 in 1 cm3 ?
1 2 3 4
6%
25%
52%
18%
1. 109
2. 1027
3. 1021
4. 10343
Why is nanotech. so important?
0.4 nm
In the solid, there is 1 atom per 0.4 x 0.4 x 0.4 nm3
So, 1 atom per 0.064 nm3 There are 1/0.064 atoms per nm3
This is, on average, ~ 16 atoms per nm3
How many nm3 in 1 cm3 ?
??107 x 107 x 107 = 1021 1 cm3 = 1021
nm3
There are approximately 1022 atoms in 1 cm3 of a solid.
Number of stars in observable universe?
Estimates vary but ~ 1022 seems to be reasonably well accepted at present.
Number of atoms in your body is a million times greater than the number of stars in the (observable) universe!
Why is nanotech. so important?
So, there are approximately 1022
atoms in 1 cm3 of a solid.
Imagine that each atom represents a bit of information (a ‘1’ or a ‘0’).
We have, in principle, the ability to store 1022 bits of information in 1 cm3.
~ 1012 GB ( = 106 Petabytes) in 1 cm3.
Using nanotechnology, we have the potential ability to store all the data in ~ 8,000,000,000
128 GB iPads in 1 cm3.
So what?!
http://techcrunch.com/2010/08/04/schmidt-data/
