Using an atomic force microscope (AFM) selected single atoms of a silicon (111) 7x7 surface have been removed and deposited. Manipulation is purely mechanical, unlike previous demonstrations of atomic scale manipulations using scanning tunneling microscopy (STM). Technique has been dubbed nanoindention. The mechanical response of two non-equivalent surface atoms has been studied.

Principle of non-contact AFM Lennard-Jones Potential: contact AFM: Repulsive regime non-contact AFM: Attractive regime http://www.mechmat.caltech.edu/~kaushik/park/1-2-2.htm Non-Contact AFM: Tip hovers between tens and hundreds of Angstroms over sample surface. Tip oscillates at high frequency (tens -hundreds of kHz). oscillation amplitude is typically in nm range Change of Topology results in amplitude and frequency shift of cantilever. http://www.stinstruments.com/Scanning%20Probe%20Microscopy3.htm

Experimental Setup & Sample Preparation: AFM in frequency modulation scheme (FM), constant excitation mode AFM works at Low Temperature (78K) and at ultrahigh vacuum (5x10-11 Torr) Commercial AFM-Tip (k=48N/m, f0=160kHz, Q-factor: 170 000) Tip was cleaned in-situ by argon-ion bombardment for 30 min. Si (111) 7x7 surface was obtained by heating sample up to 1200 °C with subsequently cooling down from 900 °C to room temperature.

Experiment: Nanoindentation Technique Before nanoindentation Sample was ramped towards oscillating tip with 0.3 A/sec. Change of cantilever frequency and amplitude was monitored. When frequency shift jumps suddenly, ramp was stopped and sample was retracted After nanoindentation: Authors do not give success rate but state that process is normally successful

Experiment: frequency shift and amplitude change

Experiment: Nanoindentation Technique Reversed

Experiment: Change of tip due to nanoindentation

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