1. 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.

2. Principle of non-contact AFM
Lennard-Jones Potential:
contact AFM: Repulsive regime
non-contact AFM: Attractive regime
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.

3. 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: )
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.

4. 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When frequency shift jumps suddenly, ramp was stopped and sample was
retracted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

5. Experiment: frequency shift and amplitude change

6. Experiment: Nanoindentation Technique Reversed

7. Experiment: Change of tip due to nanoindentation

8. Thank you !