<< Chapter < Page Chapter >> Page >
Transmission electron microscope (TEM) is a powerful tool to investigate the lattice structure and defects on materials directly. It can easily get to atomic spacial resolution. It has been used to characterize carbon materials for a long time, from C60, carbon nanotubes (single-wall carbon nanotube and multi-wall carbon nanotube), to graphene, which is single layer graphite. Many techniques based on TEM make it more useful to image the carbon nanomaterials in both bright field and dark field .

Introduction to tem

Transmission electron microscopy (TEM) is a form of microscopy that uses an high energy electron beam (rather than optical light). A beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through. The image (formed from the interaction of the electrons with the sample) is magnified and focused onto an imaging device, such as a photographic film, a fluorescent screen,or detected by a CCD camera. In order to let the electrons pass through the specimen, the specimen has to be ultra thin, usually thinner than 10 nm.

The resolution of TEM is significantly higher than light microscopes. This is because the electron has a much smaller de Broglie wavelength than visible light (wavelength of 400~700 nm). Theoretically, the maximum resolution, d, has been limited by λ, the wavelength of the detecting source (light or electrons) and NA, the numerical aperture of the system.

For high speed electrons (in TEM, electron velocity is close to the speed of light, c, so that the special theory of relativity has to be considered), the λ e :

According to this formula, if we increase the energy of the detecting source, its wavelength will decrease, and we can get higher resolution. Today, the energy of electrons used can easily get to 200 keV, sometimes as high as 1 MeV, which means the resolution is good enough to investigate structure in sub-nanometer scale. Because the electrons is focused by several electrostatic and electromagnetic lenses, like the problems optical camera usually have, the image resolution is also limited by aberration, especially the spherical aberration called C s . Equipped with a new generation of aberration correctors, transmission electron aberration-corrected microscope (TEAM) can overcome spherical aberration and get to half angstrom resolution.

Although TEAM can easily get to atomic resolution, the first TEM invented by Ruska in April 1932 could hardly compete with optical microscope, with only 3.6×4.8 = 14.4 magnification. The primary problem was the electron irradiation damage to sample in poor vacuum system. After World War II, Ruska resumed his work in developing high resolution TEM. Finally, this work brought him the Nobel Prize in physics 1986. Since then, the general structure of TEM hasn’t changed too much as shown in [link] . The basic components in TEM are: electron gun, condenser system, objective lens (most important len in TEM which determines the final resolution), diffraction lens, projective lenses (all lens are inside the equipment column, between apertures), image recording system (used to be negative films, now is CCD cameras) and vacuum system.

Questions & Answers

what are the important of economic to accounting students with references
salihu Reply
Economics is important because it helps people understand how a variety of factors work with and against each other to control how resources such as labor and capital get used, and how inflation, supply, demand, interest rates and other factors determine how much you pay for goods and services.
Muhammad
explain the steps taken by the government in developing rural market?
Azeem Reply
contribution of Adam smith in economics
abel Reply
I will join
Dexter
I will join
Patrick
Hey
Fatima
Hey
Amir
Hello
AS
hey
Umarou
I love this book and i need extra Economic book
Amir
Hey
Amir
what's happening here
AS
I love this book and i need extra Economic book
Amir
what is the meaning of function in economics
Effah Reply
Pls, I need more explanation on price Elasticity of Supply
Isaac Reply
Is the degree to the degree of responsiveness of a change in quantity supplied of goods to a change in price
Afran
Discuss the short-term and long-term balance positions of the firm in the monopoly market?
Rabindranath Reply
hey
Soumya
hi
Mitiku
how are you?
Mitiku
can you tell how can i economics honurs(BSC) in reputed college?
Soumya
through hard study and performing well than expected from you
Mitiku
what should i prepare for it?
Soumya
prepare first, in psychologically as well as potentially to sacrifice what's expected from you, when I say this I mean that you have to be ready, for every thing and to accept failure as a good and you need to change them to potential for achievement of ur goals
Mitiku
parna kya hai behencho?
Soumya
Hallo
Rabindranath
Hello, dear what's up?
Mitiku
cool
Momoh
good morning
Isaac
pls, is anyone here from Ghana?
Isaac
Hw s every one please
Afran
Ys please I'm in Ghana
Afran
Hello
OLANIYI
pls anyone from Nigeria
OLANIYI
am a new candidate here, can someone put me 2ru
OLANIYI
hello
OLANIYI
Pls economic A level exam tomorrow pls help me
akinwale
am from Ghana
Jacob
hi
Charles
Pls economic A level exam tomorrow pls help me
akinwale
Hi
Dev
bol Diya discuss ab krega v
Dev
hello Mr. Rabindranath
Dev
what do you want Dimlare
Dev
yes tell me your desire to have it
Dev
to have what?
OLANIYI
Good luck
JOSEPH
I want to know about economic A level tomorrow pls help
Lerato
okay
Umarou
okay
Umarou
what is firms
Anteyi Reply
A firm is a business entity which engages in the production of goods and aimed at making profit.
Avuwada
What is autarky in Economics.
Avuwada
what is choice
Tia Reply
So how is the perfect competition different from others
Rev Reply
what is choice
Tia
please what type of commodity is 1.Beaf 2.Suagr 3.Bread
Alfred Reply
1
Naziru
what is the difference between short run and long run?
Ukpen Reply
It just depends on how far you would like to run!!!🤣🤣🤣
Anna
meaning? You guys need not to be playing here; if you don't know a question, leave it for he that knows.
Ukpen
pls is question from which subject or which course
Ada
Is this not economics?
Ukpen
This place is meant to be for serious educational matters n not playing ground so pls let's make it a serious place.
Docky
Is there an economics expert here?
Docky
Okay and I was being serous
Anna
The short run is a period of time in which the quantity of at least one inputs is fixed...
Anna
that is the answer that I found online and in my text book
Anna
Elacisity
salihu
Meaning of economics
Suraj Reply
It will creates rooms for an effective demands.
Chinedum Reply
different between production and supply
babsnof
Hii
Suraj
hlo
eshita
What is the economic?
Suraj
Economics is a science which study human behavior as a relationship between ends and scarce means which has an alternative use.
Mr
what is supply
babsnof
what is different between demand and supply
Debless Reply
Demand refers to the quantity of products that consumers are willing to purchase at various prices per time while Supply has to do with the quantity of products suppliers are willing to supply at various prices per time. find the difference in between
Saye
Please what are the effects of rationing Effect of black market Effects of hoarding
Atty Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Carbon nanotubes. OpenStax CNX. Sep 30, 2013 Download for free at http://cnx.org/content/col11576/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Carbon nanotubes' conversation and receive update notifications?

Ask