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NANOWeek:The Power of Microscopes
•Optics•Visible light•Optical microscopes and telescopes•Scanning electron microscope
The Metric Scale is relevant to LIFE
1m = 2nd grade child 2.1m = Shaquille O’Neill 1/100m = 1 cm =~ width of pinky finger 1/1000m = 1 mm =~width of a dime 1/1,000,000 = 1 um (micron) 1/1,000,000,000 = 1nm
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The Nanometer Scale:
One inch equals 25.4 million nanometers. A sheet of paper is about 100,000
nanometers thick. A human hair measures roughly 50,000
to 100,000 nanometers in diameter. Your fingernails grow one nanometer
every second.
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A prism can separate white light into all the colors of the rainbow
Image taken from www.opticalres.com
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How do we see?
target
source
detector…and often you’ll need a lens
Magnifying Glass
Magnification: 2-10x (Loupes 30x)
One lens (Many Lenses and Prisms)
Usually a biconvex lens - both sides are convex
Focal Length
MagnifiedRight Side Up
ShrunkUpside Side Up
Focal Length
Activity: Assemble the Telescope!
Arrrrgh!
Microscope
Light Source
Stage and Sample
Objective Lens
Ocular Lens (Eyepiece)
Magnification
Objective Lenses4x Magnification10x Magnification40x Magnification100x Magnification
10x Magnification
Total Magnification:40x, 100x, 400x, 1000x
Other techniques: Feature Size
Digital Microscope
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Example Image
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Scale
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What Comes Next?
How do we view things smaller than the wavelength of light?
What do we actually “see” when we use such techniques?
http://www.mrs.org/s_mrs/doc.asp?CID=1803&DID=171434
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Basic SEM Idea
e-e-
e-
e-
e-
e-
e-
e-
e-
e-e-
Some are absorbed
Some are “reflected”
Some is absorbed
Some light is “reflected”
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Water Hose and Splash
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The “Splash”
http://www4.nau.edu/microanalysis/Microprobe-SEM/Signals.html
Primary electrons come from the beam
Some electrons scatter back (BSE), and they
move very fast
Other secondary electrons (SE) are
dislodged and move more slowly
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The Electron Beam Column
http://bioweb.usu.edu/emlab/TEM-SEM%20Teaching/How%20SEM%20works.html
Beam created from heated filament
Beam travels through a vacuum
Electro-magnetic fields act as lenses
Scattered and “secondary” electrons are detected
Electron beam hits the sample in a precise
location
Beam scans back and forth
Scanning Electron Microscope (SEM)
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