Редактирование: Molecular Manufacturing (раздел)

= Mechanosynthesis of Diamondoid =

Mechanosynthesis is the synthesis of chemical structures catalyzed by mechanical pressure and constraints, or, simply, the use of mechanical force to direct and alter the course of chemical reactions. For example, the animations to the left show a reversible mechanosynthethic reaction in which an acetylene dimer is placed on a diamond C(100) surface and then removed, using an atomic force microscope with a special tip geometry.

[[File:AcetyleneDeposition.gif|right]]
[[File:AcetyleneAbstraction.gif|right]]

Mechanosynthesis of diamond, specifically, is the synthesis through this mechanical chemistry of diamond, a stiff polycyclic structure.

[[File:assemblers.jpg|400px|center]]

The evidence for mechanosynthesis can be traced back to the historic 1989 spelling of the IBM logo using 35 Xenon atoms in a surface of Nickel by Don Eigler and Erhard K. Schweizer. However, this experiment took place a few degrees above absolute zero, and no covalent bonds were formed.

In 2003, Oyabu et al.<ref>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://prl.aps.org/abstract/PRL/v90/i17/e176102 abstract], [http://physics.aps.org/story/v11/st19 APS story].</ref> first demonstrated mechanosynthesis on a Silicon surface using an atomic force microscope to remove an atom from the surface, then place it again on the same position, again at liquid helium temperatures.
[[File:Mechanosynthesis_of_Si.gif|thumb|left|'Si' spelt on a Silicon surface using mechanosynthesis]]

[[File:MechanosynthethicReactions.jpg|thumb|Mechanosynthethic Reactions]]

[[File:Drexler Arm assembly line.jpg|thumb|A Drexler Arm in an assembly line configuration.]]


== Minimal Toolset for Positional Diamond Mechanosynthesis ==

The landmark paper by [[Ralph Merkle]] and [[Robert Freitas]], published in 2008 by the Journal of Computational and Theoretical Nanoscience, shows a minimal set of tools that can be used to synthesize unstrained diamond of arbitrary size, and also synthesize ''copies of itself''. Each tooltip is designed to work on a flat surface of (Initially) Hydrogen-terminated diamond and can be moved attached to a [[#Scanning Probe Microscope|Scanning Probe Microscope]] to control their motion. Bootstrap strategies -- Through which ordinary tools are used to produce the simplest tips, which are then used to produce the rest of the set -- are provided, along with reaction sequences for the construction of diamond and fullerene.

The paper is: ''Robert A. Freitas Jr., Ralph C. Merkle, "A Minimal Toolset for Positional Diamond Mechanosynthesis," J. Comput. Theor. Nanosci. 5(May 2008):760-861;'' and is available [http://www.molecularassembler.com/Papers/MinToolset.pdf here].

=== Overview ===

[[File:Mechanosynthesis of fullerene.jpg|thumb|left|Mechanosynthesis of an atomically-precise nanotube]]

The rapid, atomically-precise construction of macroscale objects of varied molecular structures is the eventual goal of molecular nanotechnology. The paper presents the more modest and specific objective of ultra-high-vacuum-based diamondoid mechanosynthesis using the positional control granted by an [[#Scanning Probe Microscope|Scanning Probe Microscope]].

Following the 1992 publication of [[Eric Drexler|Drexler's]] [[#Nanosystems: Molecular Machinery, Manufacturing and Computation|''Nanosystems'']], in which some basic mechanosynthethic reaction pathways and sketches of possible tooltips, in 1997 [[Ralph Merkle|Merkle]] outlined the "hydrocarbon metabolism", a set of reaction pathways for DMS, which used nine different tooltips and several intermediate tooltips, some of which were not defined entirely, and used at least six different elements and one unspecified transition metal, and yet another unspecified "vitamin molecule" possibly requiring additional elements. Moreover, most reaction sequences were not completely specified and reaction closure was not 100%. It did not specify how the toolset may be constructed or what handle structures may have been required.

The Minimal Toolset paper proposes a 100% process closure which can be achieved using a minimal set of tools for mechanosynthesis, consisting of three primary tools: Hydrogen Abstraction ('''HAbst'''), Hydrogen Donation ('''HDon'''), and Dimer Placement ('''DimerP'''). These are assisted by six auxiliary tools, the discharged versions of Hydrogen Abstraction ('''AdamRad''') and Hydrogen Donation ('''GeRad'''), and intermediate structures: Methylene ('''Meth'''), Germylmethylene ('''GM'''), and Germylene ('''Germ'''). And finally, a Hydrogen Transfer tool that is a compound form of the HAbst and GeRad tools.

=== Tooltips ===

=== Tool Fabrication ===

=== Products ===

==== Diamond ====

==== Lonsdaleite ====

==== Fullerene ====

==== Ethylation, Propylation, and Related Reactions ====

==== Hydrocarbon Chains ====

== Molecular Assembler ==