PROJECT TITLE :
Preparation of scanning tunneling microscopy tips using pulsed alternating current etching
An electrochemical method using pulsed alternating current etching (PACE) to provide atomically sharp scanning tunneling microscopy (STM) tips is presented. An Arduino Uno microcontroller was used to regulate the number and length of the alternating current (AC) pulses, permitting for ready optimization of the procedures for each Pt:Ir and W tips using a single apparatus. W tips ready using constant and pulsed AC power were compared. Tips fashioned using PACE were sharper than those etched with continuous AC power alone. Pt:Ir tips were ready with an initial coarse etching stage using continuous AC power followed by fine etching using PACE. The number and potential of the finishing AC pulses was varied and scanning electron microscope imaging was used to match the results. Finally, tip quality using the optimized procedures was verified by UHV-STM imaging. With PACE, a minimum of seventyp.c of the W tips and 80% of the Pt:Ir tips were of sufficiently top quality to obtain atomically resolved images of HOPG or Ni(111).
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