Experimental demonstrations of single atom manipulation

Placing matter atom by atom is indeed possible.
Even with our still very crude big and clunky current technology.
There already have been several demonstrations.

• 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 atoms stay put at much higher (but still cold) temperatures (liquid nitrogen)
• A bit of scaling up was shown too, but scaling to bigger products that retain positional atomic precision was so far (2022) all done only
  – on the easier purely metallic systems and
  – with 2D hydrogen abstraction on silicon

Diamondoid AP tooltips

Single atom manipulation experiments with atomically precise nanoscale tooltips:

There supposedly where somewhen (2021) done some experiments on an atomically precise nanoscale hydrogen abstraction tooltip (HAT): ( http://www.zyvex.com/nanotech/Habs/paper.html )

Specifically one of the tips supposedly tried was

• an ethyne radical •C≡C-R
• on the tip of an adamantane cage
• linked via three -S-CH2- bridges to a gold surface.

Video (timestamp 35:44): [1]

• One diamondoid tool was created and verified
• abstraction of an atom (presumably hydrogen) from an SPM tip may have been demonstrated (?) – UV cleared
• development of two more tools was planned supposedly
• project end was 2021-12 supposedly
• eventually science or nature paper on this …
• Also mentioned: Expected benefit 100x to 1000x speedup from MEMS AFM/STM (UT Dallas)

Video (timestamp 13:57): [2]

• Location: UCLA (University of California, Los Angeles)
• Funding: seems switched to CBN (Canadian Banknote Company) – Now core of Canadas APM program?
• Info from vendors: Several dozens of scienta omicron low temp STM machines (developed by UCLA) where orderedby "them".
• Lowest TRL (technology readiness level) effort in the "group" ( DOE=>AMO? – https://www.energy.gov/eere/amo/ )

Corresponding slides 21 and 12 here: [3]

Somewhat cold to warm nonmetals

Extraction an re-deposition a a single silicon atom (at 78K) was experimentally demonstrated.

Crude but more than hydrogen:
There where some earlier experiments (see external links below for details)

• on relevant materials (strong covalently bonding nonmetallic silicon)
• at revelant temperatures (liquid nitrogen rather than liquid helium)

removing adding a single silicon atoms from a surface or
less relevantly swapping silicon and tin (tin being same group as silicon but two periods lower).
This was still a quite crude process though involving a lot of taping till eventually the desired reaction happened.

More advanced but only hydrogen:
Atomically precise hydrogen abstraction on silicon has been experimentally achieved by
means of conventional etched metallic STM tips (likely tungsten or Pt/Ir).
This is called PALE patterned atomic layer epitaxy. (See: Patterned layer epitaxy)
A big current limitation is that this cannot yet go to 3D.
Likely due to the huge inertial mass of macroscale SPM microscope piezo crystals.
Going to MEMS SPM systems might fix that. Hopefully.

Related to this it has been discovered that abstraction of hydrogen can lead to bi-stable switchable surface configurations.
Flipping these can cause chain reactions like falling dominoes and this could eventually be used for computation.
(2019) video at 10:29
https://www.robertwolkow.com/

And more things: Far Faster Fabrication of Binary Atomic Silicon Logic Circuitry

Ultracold to cold metals

Cobalt atoms precisely arranged on copper a surface. This was done at very low temperature under UHV. This is a 3D surface representation of a non 3D property that was strongly "smoothed" in post processing. Details in the main text. (Disclaimer: This wiki is not in any way associated with the National Institute of Standards and Technology - NIST) Side-note: There's a much more famous similar image made by IBM employees but it's not under a free license)

There have been demonstrations of single atom manipulation
both of noble gas atoms and metal atoms on metal surfaces.
This was initially done at very low temperatures.
I.e. liquid helium temperatures. Especially for noble gas atoms.

Unfortunately this is not too relevant for
mechanosynthesis of materials with much stronger bonds at much higher temperatures.
But it demonstrated the fundamental possibility of the manipulation of single atoms.

Positioning weakly bonding atoms at low temperatures has advanced quite far.
There are quite a number of examples of grids with atoms placed to atomic precision.

Examples:

• bigger data storage like grids: Paper: A kilobyte rewritable atomic memory (chlorine-terminated Cu(100) stable at 77K - vacancies moved around)
• artistic famous animation A Boy and His Atom (Carbon monoxide on copper at 5K)
• assembly of quantum corrals (iron on copper)
• the famous IBM atoms (Xenon on nickel al liquid helium temperatures)

Relation to direct and incremental path

Pushing single atom manipulation capabilities forward can probably be considered as part of the direct path.
Progress here seems painstakingly slow (state 2017, early signs of accelerating 2022).

Results from here may eventually become integratable with results from the incremental path.
There are severe complications for marrying results of the pathways though:

• either the incremental path need to go all the way to reach PPV vacuum systems – a tall order we are still far from (2022)
• or in-solution-(piezo)mechanosynthesis needs to be prototyped too. This has not yet been started. Not even theoretically (2022)

State 2022: Given the still slow experimental progress in single atom manipulation
compared to the astoundingly accelerating progress rate in de-novo foldamer development
it currently looks like that the incremental path will gain a significant head start.

So at this point it may seem that systems made via the incremental path may
be the first to arrive at a point where atomically precise positional nano manipulator systems can be built.
A major difference of such systems to direct path systems is
that a lot of mere topological atomic precesition may be involved.
If sufficient sophistication is eventually gets reached,
then the results of experimental work in single atom (and small molecule fragment) manipulation
(as discussed on the present page here) can be integrated.

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.)

Real science - Lying images

Be aware that images from various forms of SPM microscopy
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 which is total fantasy. (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 researchers can be (and are) very tempted to remove high spacial frequency part of the images to make images much prettier. Basically a brutal low pass (or band pass) filter is applied. 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)

Related

• Scanning probe microscopy
• Mechanosynthesis
• Why gemstone metamaterial technology should work in brief
• Ultra high resolution atomically resolving imaging via SPM microscopy

External links

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)

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• 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)
Press release on osaka university page. – (pdf)