Scanning probe microscopy upwards into 3D

(wiki-TODO: Add figures from the paper.)

Experimentally demonstrated:
With stiff cantilever AFM using the CO probing method:

• First using STM (current through the picked up CO) slightly off-site to reproducibly get a reference height
• Then going up and in nc-AFM constant height mode, and scanning the very high up top flat area of
  small polyadamantanes (nanodiamonds). Note that this is higher up than the length of the probing CO molecule!
  And there at the top well resolving the diamond (111) face hydrogen termination structure.
• Avoiding to pick up the extremely weakly to gold bond polyadamantanes onto the SPM-needle-tip apex (or toppling the vertical standing ones over).
• Scanning of hydrogen atoms that were hidden due to lying slightly lower by ramping down the scanning height

Why may this be relevant and promising?

Why is this a significant advance pointing to the eventual feasibility of
force applying mechanosynthesis of 3D structures like crystolecules?

Scanning 3D structures so far has been an Achilles heel of scanning probe microscopy (both STM and stiff cantilever AFM).
(wiki-TODO: Link the paper of nc-AFM scanned DNA, showing that images of slightly higher structures without flat top typically become distorted or at least non-interpretable.)

Here it has been shown that one can "jump up" a huge deal and scan up there with no losses in resolution and interpretability.
And without crashing the SPM-needle-tip-apex (big and blunt at this scale) into the high molecules on the surface

As is what the (for this reason not used) constant feedback (~ stiffness) scanning mode would do.
Scratching whit the "blunt" SPM-needle-tips side up the sharp edge of the atomically precise product.
See: SPM user interfaces

Notes

Yes, This experiment was merely very gentle scanning. No strong bonding interactions.
But with structures stronger anchored to the supporting surface
much stronger interactions for should be possible too.
Potentially enabling force applying mechanosyntehsis being performed up there up top.

The ramping must have been a significant effort judging from the papers mention of (being glad to) not needing to do it again due to the associated slight slant.
There may be a lot to be gained be improvement on SPM control software fro automating such ramping operations and related operations.
related: SPM user interfaces

The flat top of these polyadamnatanes was really critical here to get well interpretable images (without computationa simualtions even).
Force applying mechanosyntehsis may operate much like a 3D-printer, adding material layer-by-layers, so one always has quite flat top to work with.

Related pages

• Stiff cantilever AFM & Scanning probe microscopy
• Mechanosynthesis & Mechanosynthesis (disambiguation)
• Why gemstone metamaterial technology should work in brief
• SPM user interfaces

External links

★ [Ebling2018] Ebeling, Daniel & Šekutor, Marina & Stiefermann, Marvin & Tschakert, Jalmar & Dahl, Jeremy & Carlson, Robert & Schirmeisen, André & Schreiner, Peter. (2018). Assigning the absolute configuration of single aliphatic molecules by visual inspection. Nature Communications. 9. 10.1038/s41467-018-04843-z.