Notre Dame extended Research Community NANOWeek: The Power of Microscopes Optics Visible light Optical microscopes and telescopes Scanning electron microscope

The Metric Scale is relevant to LIFE  1m = 2 nd 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 um thick nm wide

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. 3

4

A prism can separate white light into all the colors of the rainbow Image taken from

6 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 Magnified Right Side Up Shrunk Upside Side Up Focal Length

9 Chromatic Aberration  A kind of distortion (color)  Can be fixed to a certain extent  Imperfections also lead to distortions  Tilting the lens leads to another distortion

10 Examples of Chromatic Aberration

Microscope Light Source Stage and Sample Objective Lens Ocular Lens (Eyepiece)

Magnification Objective Lenses 4x Magnification 10x Magnification 40x Magnification 100x Magnification 10x Magnification Total Magnification: 40x, 100x, 400x, 1000x Other techniques: Feature Size

Digital Microscope

14 Example Image

15 Scale

16 What Comes Next?  How do we view things smaller than the wavelength of light?  What do we actually “see” when we use such techniques?

17 Scale  SEM Feature Sizes  Down to 1 nm for best scopes  Maximum around 500,000x magnification  Viewing Nanomagnets  Feature Size: 5-10nm

18 Basic SEM Idea e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- Some are absorbed Some are “reflected” Some is absorbed Some light is “reflected”

19 Water Hose and Splash

20 Splash Analog  How it helps  E-Beam and Water Stream  Scattering and Splash  The beam moves back and forth (scan)  How it doesn’t help  Electron beam is created by magnetic field  The beam gets wider and thinner  The electrons penetrate the surface  Electrons can be selectively detected Be clear when using analogs!

21 The “Splash” 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

22 The Electron Beam Column 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)