Experimental demonstrations of single atom manipulation
There already have been several demonstrations that placing matter atom by atom is indeed possible even with our still very crude big and clunky current technology.
- At first this was limited to extremely low temperatures (liquid helium) metallic surfaces and scanning tunneling microscopes.
- Later it was shown that (as expectable) on covalent surfaces things stay put at much higher (but still cold) temperatures (liquid nitrogen)
- A bit of scaling up was shown too but this was all done on the easier purely metallic systems.
Pushing single atom manipulation capabilities forward can generally considered part of the direct path. Since progress here seems painstakingly slow (state 2017), a great hope is that the incremental path can much faster build up systems in which once they reach sufficient sophistication the results of the single atom manipulation attempts (discussed here) can be integrated.
Real science - Lying images
Note: Images are often halfway pure reality halfway pure fantasy.
One intuitively tends to interpret brightness as topographic hight but in STM (scanning tunneling microscopy) images brightness actually only gives information about electron density (more concretely: local electron density of states at the probed bias voltage level). This misinterpretation is often taken one step further and the pseudo-height is rendered as real 3D surface with the peaks throwing shadows. (Probably mainly because it looks pretty).
Also since one is pushing the limits SPM (STM and AFM) images are usually very noisy. Since atomic lattices show high regularity/periodicity one researchers can be tempted to remove high frequency part of the images to make images prettier but this also removes information that might have been more than just random noise. (Method: Fourier transformation (FT) this gives an "image spectrum image" -> cutting of outer high frequency border leaving in important peaks -> backward FT)
pure metals - easiest in lab - least useful in advanced APM
The early research illustrates nicely why pure metals are not too suitable for advanced APM.
- Extreme cooling is needed to keep lone surface adsorbed atoms from wildly hopping around (diffusion).
- The free electron gas of metals (especially a 2D sheet on the surface) may complicate mechanosynthesis (just makes EE harder.)
(TODO: Add illustrative image to article)
No mechanical force only tunneling current – metallic solids & noble gas atoms – ultra-cold
- IBM: IBM_(atoms) (Xe on Ni – early famous work)
- IBM: A Boy And His Atom: The World's Smallest Movie – Wikipedia: A_Boy_and_His_Atom (carbon monoxide CO on Cu – 5K)
- A kilobyte rewritable atomic memory video (chlorine Cl on copper Cu)
- NIST: https://en.wikipedia.org/wiki/File:NIST_HipHopAtomLogo.jpg (Co on Cu)
- NIST: quantum corral (Co on Cu 7K & 4.3K)
- Quantum corral: Crommie M. F., Lutz C. P., Eigler D.M. Confinement of electrons to quantum corrals on a metal surface // Science. 1993. V. 262. P. 218–220. – (Fe on Cu) picture of 3D printed model
Mechanical force involved – covalent solids – only "slightly" cold
Swapping tin and silicon atoms:
Yoshiaki Sugimoto 1, Pablo Pou 2, Oscar Custance 3, Pavel Jelinek 4, Masayuki Abe 1, Rubén Pérez 2 & Seizo Morita 1. Complex patterning by vertical interchange atom manipulation using atomic force microscopy Science 322 , 413-417 (2008). (DOI link) (pdf)
Ripping out and redepositing sigle silicon atoms on silicon surface:
Noriaki Oyabu, Oscar Custance, Insook Yi, Yasuhiro Sugawara, Seizo Morita, "Mechanical vertical manipulation of selected single atoms by soft nanoindentation using near contact Atomic Force Microscopy," Phys. Rev. Lett. 90(2 May 2003):176102; http://link.aps.org/abstract/PRL/v90/e176102
pdf on academia.edu (78K)