From the Human Eye Down to Microscopes at the Nano-Scale

1. From the Human Eye Down to Microscopes at the Nano-Scale Michael Crocker Valerie Goss Pat Mooney Rebecca Quardokus

2. Outline Discussion of Optics History Ranges of Visual Resolution Scanning Electron Microscopy (SEM) Fundamentals Operation Scheme Atomic Force Microscopy (AFM) Scanning Tunneling Microscopy (STM)

3. Scanning Bunny A distant cousin of the energizer bunny who helps to explain nanoscience concepts. WELCOME PENN HIGH SCHOOL

4. How do we see an object? source target detector …and often you’ll need a lens

5. Requirements of Vision • The light that reaches the eye must have a color between red (760nm) and blue (400nm) – or a mixture of these colors • The light that reaches the eye must be sufficiently bright – usually requires a sufficiently bright source www.uvabcs.com/uvlight-typical.php , August 31, 2009 UV UV UV C B A visible light infrared 760 wavelength in nm 3000 290 320 760 400

6. Object and Source Matching

7. Seeing Atomic Structure • Light must be about 0.1nm in wavelength to see atomic structure: x-rays • But our eyes can’t detect x-rays - 0.1nm light - (5000 times smaller wavelength than we can see) • Options • Use x-rays and detector (to replace the eye) • Use particles (e.g. electrons) and detector • Electrons of the appropriate wavelength are easier to produce and direct than light – Scanning Electron Microscope (SEM) • Alternate imaging techniques • Atomic Force Microscope (AFM) • Scanning Tunneling Microscope (STM)

8. Scanning Electron Microscope Michael Crocker

9. Let’s bounce something else at the surface! e- e- e- e- e- e- e- e- e- e- e- Basic Idea? Animal sight and traditional microscopes collect deflected light Some are “reflected” Some are absorbed

10. Electron Beam Column Beam created from heated filament Beam travels through a vacuum Electro-magnetic fields act as lenses Electron beam hits the sample in a precise location Scattered and “secondary” electrons are detected Beam scans back and forth http://bioweb.usu.edu/emlab/TEM-SEM%20Teaching/How%20SEM%20works.html

11. Electrons Hit Surface and Detection Primary electrons come from the beam Some scatter back, others dislodge electrons http://www4.nau.edu/microanalysis/Microprobe-SEM/Signals.html

12. Example Images http://gsc.nrcan.gc.ca/labs/ebeam/sem_gallery_e.php

13. Atomic Force Microscope Valerie Goss

14. What is the AFM? An analogue! We can sense with our hands by touching.

15. AFM cantilever and AFM tips www.veeco.com

16. The powerful, versatile AFM Resolutions: X and Y 2 -10 nm Z 0.05 nm Microstructure of solids: CD, glass beads, circuits Biological samples: skin cross section, viruses, bacteria, blood, DNA and RNA ~30 um scan www.nanotech-now.com/.../antonio-siber.htm Aug 27, 2009

17. Scanning Tunneling Microscope Rebecca Quardokus

18. Electrons tunnel! With a higher probability than cars STM measures the current created by tunneling electrons Scanning Tunneling Microscopy (STM) Images courtesy of http://www.ieap.uni-kiel.de and www.renault.com

19. Scanning Tunneling Microscopy (STM) C60 “Bucky Balls” Each C60 diameter is ~ 10Å 1 Å = 1x 10-10 m Image courtesy of http://nano.tm.agilent.com

20. Scanning Tunneling Microscopy (STM) Xenon on Nickel Individual atoms? That’s small! Iron on Copper Images courtesy of http://www.almaden.ibm.com

21. I’ll show you more in the microscope laboratory!