3. 5 kV  = 0.5 nm

4. Atomic resolution TEM image

5. EBPG (Electron beam pattern generator) 100 kV  = 0.12 nm

6. SNOM To locate single molecules: Optical microscopy: -fluorescence (labeling) -particle tagging (-electron microscopy)

7. Piezoelectric (Voltage – Displacement) Precise tip control is achieved with Piezoelectrics Displacement accurate to ±.05 Å PZT = (Pb,Zr)TiO 3

8. Basic Principles of STM Electrons tunnel between the tip and sample, a small current I is generated (10 pA to 1 nA). I proportional to e -2κd, I decreases by a factor of 10 when d is increased by 1 Å. d ~ 6 Å Bias voltage: mV – V range

9. Copper Surface Silicon

10. Silicium-oppervlak met stappen (Bron: Sandia Nat.Labs.) Si(100)

11. Two Modes of Scanning Constant Height Mode Constant Current Mode Usually, constant current mode is superior.

12. Instrumental Design Continued Tips Cut platinum – iridium wires Tungsten wire electrochemically etched Tungsten sharpened with ion milling Best tips have a point a few hundred nm wide Vibration Control Coiled spring suspension with magnetic damping Stacked metal plates with dampers between them

13. Interpreting STM Images Hydrogen on Gadolinium “Topography” model good for large scale images, but not for the atomic level. Electron charge density model more accurate for atomic level images. Best model requires complex quantum mechanical considerations

14. Atomic Force microscope (Scanning Force Microscope) Piezo Electric positioner Feedback electronics Laser diode Deflection detector Flexible cantilever Probe tip display

15. AFM Tip

16. yy zz l L l ~ 100  m L ~ 3 cm  z ~ 1000  y !!! Detection: beam deflection Optical lever amplification

17. Scanning modes Constant heightConstant force Contact modeTapping mode High frictionNo friction forces

18. Resolution: scanning probe microscope objecttip geometry image Tip convolution is not linear: results DO NOT add up Resolution is depends on tip AND sample

19. Imaging and manipulation of Carbon nanotubes

20. Millipede 1024 tips