Cause of limited imaging by EAOGe-C2I molecules on H-passivated SPC apexes

Determine why only a subset of EAOGe-C2I molecules adsorbed on a Si(100)-2x1 sample produce effective reflected-probe images of a hydrogen-passivated Silicon Probe Chip (SPC) apex in inverted-mode scanning tunneling microscopy, and characterize the mechanism that governs whether a molecule can image the H:Si(100)-2x1 SPC apex well.

Background

In Supplementary Section 8, the authors describe preparing the same Silicon Probe Chip (SPC) before and after hydrogen passivation and note that only some of the surface-bound EAOGe-C2I molecules are able to image the hydrogen-passivated probe apex effectively in inverted-mode STM. They observe that this behavior is not explained by the sample change (the sample remains the same), highlighting an unresolved issue in how molecular imagers interact with H-passivated SPC apexes.

This uncertainty affects reproducibility and selection of suitable imagers for mechanosynthesis and characterization, since understanding which molecules remain effective after passivation is important for sequential reactions and apex verification.

References

Note that because the same sample is used in both cases, one immediate observation that can be made from this data is that only a subset of the molecules on the surface image the H-passivated SPC well. It is yet unclear why this is the case.

— Inverted-Mode Scanning Tunneling Microscopy for Atomically Precise Fabrication  (2512.24431 - Barrera et al., 30 Dec 2025) in Supplementary Section 8 (More information on H-passivation of SPCs)