If you read the detailed literature about technical processes underlying molecular manufacturing, you may come across the terms 'mechanochemistry' or 'mechanosynthesis'. What do these big words mean?
Definitions by committee are evolving at Wikipedia, which we've linked above. But here is CRN's simple explanation (prepared by Chris Phoenix, Director of Research) of how mechanochemistry works...
It's a bit like enzymes: you fix onto a molecule or two, then twist or pull or push in a precise way until a chemical reaction happens right where you want it. This happens in a vacuum, so you don't have water molecules bumping around. It's a lot more controllable. If you want to add an atom to a surface, you start with that atom bound to a molecule called a "tool tip" at the end of a mechanical manipulator. You move the atom to the point where you want it to end up. Limited molecular nanotechnology deals only with stiff 3D molecules like diamond, so you know where each atom is relative to its neighbors, and they don't flop or twist around like protein. You move the atom next to the surface, and make sure that it has a weaker bond to the tool tip than to the surface. When you bring them close enough, the bond will transfer. This is ordinary chemistry: an atom moving from one molecule to another when they come close enough to each other, and when the movement is energetically favorable. What's different about mechanochemistry is that the tool tip molecule can be positioned by direct computer control, so you can do this one reaction at a wide variety of sites on the surface. Just a few reactions give you a lot of flexibility in what you make.
And for those who like pictures...
MECHANOSYNTHETIC REACTIONS — Based on quantum chemistry by Walch and Merkle [Nanotechnology, 9, 285 (1998)] — To deposit carbon, a device moves a vinylidenecarbene along a barrier-free path to bond to a diamond (100) surface dimer, twists 90° to break a pi bond, and then pulls to cleave the remaining sigma bond.
How very, very interesting that you would now post a piece which attempts to define the term mechanosynthesis. This is rather a step froward from your position a few weeks ago regarding the usefulness of definitions.
I wonder which particular debate might have prompted your decision to post this piece?
I ask you once again whether you give Richard Jones permission to post the debate at "Soft Machines".
Alternatively, please see Jim Moore and Richard Jones' comments under http://crnano.typepad.com/crnblog/2005/01/creativity_and_.html
and reconsider posting our debate on the CRN website.
Philip
Posted by: Philip Moriarty | January 09, 2005 at 03:28 AM