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Towards Atom-by-Atom Fabrication: Mechanosynthetic donation and abstraction
Authors:
Brandon Blue,
Mathieu Morin,
Alex Inayeh,
Rosemary Cranston,
Cameron J. Mackie,
Marc Savoie,
Adam Bottomley,
Christian J. Imperiale,
Zehra Ahmed,
Rafik Addou,
Aly Asani,
Eduardo Barrera-Ramirez,
Jeremy Barton,
Doreen Cheng,
Megan Cowie,
Chris Deimert,
Tyler Enright,
James Zhangming Fan,
Robert A. Freitas Jr,
Alan T. K. Godfrey,
Ryan Groome,
Si Yue Guo,
Kareem A. Clarcia,
Aru Hill,
Taleana Huff
, et al. (33 additional authors not shown)
Abstract:
Enabled by inverted-mode scanning tunneling microscopy (IM-STM) and the use of functionalized molecular tools, we demonstrate positionally-controlled mechanosynthetic addition (donation) of carbon and subtraction (abstraction) of silicon atoms on a model build site: atomically clean and crystalline Si(100). The resulting structures represent the first demonstrations of an emerging ability to manip…
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Enabled by inverted-mode scanning tunneling microscopy (IM-STM) and the use of functionalized molecular tools, we demonstrate positionally-controlled mechanosynthetic addition (donation) of carbon and subtraction (abstraction) of silicon atoms on a model build site: atomically clean and crystalline Si(100). The resulting structures represent the first demonstrations of an emerging ability to manipulate radical chemistry with positional control of specific atoms and moieties in 3D. Furthermore, by comparing the behavior of molecular tools designed for atomic donation versus abstraction, we highlight general principles governing molecular tool design for selective and reliable mechanosynthetic functionality.
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Submitted 11 June, 2026;
originally announced June 2026.
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Atomically precise mechanosynthesis of carbon structures on hydrogenated Si(100) by inverted-mode STM
Authors:
Megan Cowie,
Chris Deimert,
Ryan Groome,
Alex Inayeh,
Robert J. Kirby,
Cameron J. Mackie,
Jonathan Myall,
Sam Rohe,
Luis Sandoval,
Khalil Sayed-Akhmad,
Bheeshmon Thanabalasingam,
Reid Wotton,
Rafik Addou,
Aly Asani,
Brandon Blue,
Adam Bottomley,
Kareem A. Clarcia,
Tyler Enright,
James Zhangming Fan,
Robert A. Freitas Jr.,
Alan T. K. Godfrey,
Si Yue Guo,
Aru Hill,
Taleana Huff,
Mark Jobes
, et al. (22 additional authors not shown)
Abstract:
The ability to build atomically precise structures on surfaces with complete control over both atomic placement and chemical bonding remains a central challenge in nanoscale fabrication. Here, we demonstrate simultaneous spatial and chemical control over the mechanosynthetic fabrication of carbon structures. Using inverted-mode STM, C$_2$ units are donated from surface-deposited molecules to pre-p…
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The ability to build atomically precise structures on surfaces with complete control over both atomic placement and chemical bonding remains a central challenge in nanoscale fabrication. Here, we demonstrate simultaneous spatial and chemical control over the mechanosynthetic fabrication of carbon structures. Using inverted-mode STM, C$_2$ units are donated from surface-deposited molecules to pre-patterned reactive sites on a hydrogen-passivated Si(100) surface. We demonstrate single-site C$_2$ donation, spatially patterned multi-site C$_2$ donation, and the stepwise assembly of polyyne structures through successive C-C bond formation. Together, these results establish controlled mechanosynthetic donation as a foundational capability for programmable atomically precise fabrication.
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Submitted 26 May, 2026;
originally announced May 2026.
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Inverted-Mode Scanning Tunneling Microscopy for Atomically Precise Fabrication
Authors:
Eduardo Barrera,
Bheeshmon Thanabalasingam,
Rafik Addou,
Damian Allis,
Aly Asani,
Jeremy Barton,
Tomass Bernots,
Brandon Blue,
Adam Bottomley,
Doreen Cheng,
Byoung Choi,
Megan Cowie,
Chris Deimert,
Michael Drew,
Mathieu Durand,
Tyler Enright,
Robert A. Freitas Jr.,
Alan Godfrey,
Ryan Groome,
Si Yue Guo,
Sheldon Haird,
Aru Hill,
Taleana Huff,
Christian Imperiale,
Alex Inayeh
, et al. (35 additional authors not shown)
Abstract:
Scanning Tunneling Microscopy (STM) enables fabrication of atomically precise structures with unique properties and growing technological potential. However, reproducible manipulation of covalently bonded atoms requires control over the atomic configuration of both sample and probe - a longstanding challenge in STM. Here, we introduce inverted-mode STM, an approach that enables mechanically contro…
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Scanning Tunneling Microscopy (STM) enables fabrication of atomically precise structures with unique properties and growing technological potential. However, reproducible manipulation of covalently bonded atoms requires control over the atomic configuration of both sample and probe - a longstanding challenge in STM. Here, we introduce inverted-mode STM, an approach that enables mechanically controlled chemical reactions for atomically precise fabrication. Tailored molecules on a Si(100) surface image the probe apex, and the usual challenge of understanding the probe structure is effectively solved. The molecules can also react with the probe, with the two sides of the tunnel junction acting as reagents positioned with sub-angstrom precision. This allows abstraction or donation of atoms from or to the probe apex. We demonstrate this by using a novel alkynyl-terminated molecule to reproducibly abstract hydrogen atoms from the probe. The approach is expected to extend to other elements and moieties, opening a new avenue for scalable atomically precise fabrication.
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Submitted 30 December, 2025;
originally announced December 2025.