Pulse Induced Nanlithography of Graphite in H20: A Road to Chemical Linkages to the Surface
Technical rept. Jun 90-Jun 91,
CALIFORNIA INST OF TECH PASADENA DEPT OF CHEMISTRY
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The effects of tip-sample bias pulses while within tunneling distances have been investigated for graphite surfaces in contact with dry fluids, fluids containing water, and liquid water. In dry ambients, no surface modifications were observed at pulse voltages in excess of 10 V. In fluids containing water, bias pulses exceeding a threshold voltage produced pits in the graphite surface, but the threshold voltage exhibited daily fluctuations of as much as 5 V. At the threshold for surface modification, a typical pit was found to have a diameter of approximately 30 angstrom and was 3 angstrom in depth. The diameter and depth of the pits increased with pulse amplitude above the observed threshold. In pure water, a reproducible bias pulse threshold was observed, and such pulses yielded dome-like features on the surface.
- Physical Chemistry