1. June 13, 2015Sean Glass 2003 Two and three- dimensional nanoscale structures for molecular electronics Controlled self assembly of charged-stabilized gold nanoparticles into close-packed arrays

2. Executive Summary Origins of the project Initial Research The tilting method Coffee Drops & Nanoparticles? Current Status and Future plans

3. Molecular Electronics Using Individual Molecules as electronic devices Different paths to achieve molecular devices Planar Devices The Nanocell

4. Gold Nanoparticles Molecular Wires Addressable through leads into the nanocell Programmed to function as a logic device

5. Gold Nanoparticle Deposition Ideal - Hexagonal close packing Confined to within the Nanocell Not easily trapped using voltage or magnetic fields

6. SiO 2 Microsphere Deposition Photonic band gap crystals Numerous methods previously explored  Spinning  Tilting  Tapered Cell Ng et al. Nanotechnology 13 My result with 100nm Polyspheres

7. Tilting Method Simple & Controllable Setup  Reproducible  Highly Adjustable  Oven Capable

8. 1st Experiments with Tilting Setup Temperature / Concentration Constant / Varied Tilt Polyspheres and Gold Nanoparticles  Au: 60nm 100nm  PS: 50nm 100nm 500nm

9. Results Best assembly with 0 tilt Assembly at the rim of the drop Polyspheres assembly better than Au Nanoparticles Distinct layers form with 60nm Au nanoparticles!

10. Nanoparticle Deposition at the Rim Occurs at edge of drop. Caused by pinning of edge of drop to surface and capillary forces that are created as a result during evaporation From “ Capillary flow as the cause of ring stains from dried liquid drops” Robert D. Deegan*, Olgica Bakajin*, Todd F. Dupont†, Greb Huber*, Sidney R. Nagel* & Thomas A. Witten* Nature, October 22 1995?

11. Rim Characteristics Width Order Layers - steps

12. Hypothesis – Particle Motion V V-  V Velocity is proportional to height b/c h(t) * v(t) = constant (Deegan et al. Physical Review E Volume 62 Number 1) 0 tilt Significant tilt

13. Layers / steps Reproducible Consistent layer width

14. Layer Formation Control Hypothesis Depends directly on J(r) – the evaporation profile  Depends on temperature and area of evaporation  v(r) depends on J(r) and the contact angle  J(r) depends on T and surrounding environment Concentration Deegen et Al. demonstrated on a macro scale how different evaporative profiles affect deposition at the contact line

15. Ongoing work to be done with step formation / control Vary concentration, temperature, and evaporation profile while fixing tilt Computer Simulation of Model

16. Further Experiments Multiple Drops Ultrasonic bath to increase ordering IV measurements through Au NP arrays

17. Special Thanks To Professor Mark Reed Dr. Ilona Kretzschmar