VERY SHARP GOLD AND PLATINUM TIPS TO MODIFY GOLD SURFACES IN SCANNING-TUNNELING-MICROSCOPY

To induce modifications of gold (111) surface using a scanning tunneling microscope, we have developed new electrochemical procedures to obtain very sharp gold and platinum tips. The resulting geometry is very reproducible and the mean curvature radius is 10 and 5 nm for the two materials, respectively. We have studied the formation of mounds and holes obtained by applying voltage pulses using these prepared tips. The resulting modifications of sample and tip geometry are observed. The threshold pulse amplitude is related to the tip to sample distance and the material transfer is described as a metal-metal bonding.