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Individual Chemical Bond Formed With STM
WillWare writes: "Using a scanning tunneling microscope at the Free University of
Berlin, scientists have for the first time manipulated single
molecules to perform a complete
chemical reaction. (Here are
STM pictures of the reaction happening.) ...the making of C12H10
molecules from C6H5I molecules, normally carried out on a copper
catalyst and using thermal activation, has here been forced to proceed by employing one
molecule at a time at a cryogenic temperature of 20 K. The researchers
believe that new manmade molecules, never before seen in nature, can
be engineered in this way, including the selective detachment or
replacement of parts of larger molecules for individual assembling of
molecular based nano-devices. The official article appears in Physical
Review Letters, 25 Sept." Nanites. That's all I have to say.
An STM is an interesting gadget. You have a very sharp probe (the point is a single atom) which hovers over the sample. Everything is electrically conductive except for the gap between the probe and the sample, typically a few nanometers. The gap is an insulator except for the ability of electrons to tunnel across the gap. The current flow due to tunneling is quite sensitive to the gap size.
Set up a servo to control the height of the probe, holding the tunneling current constant (the probe is moved with piezoelectric crystals). Horizontally sweep the probe in a TV-like raster pattern, recording the probe's height as a function of horizontal position, add false color, and voila, you've imaged atoms.
Here is a more detailed description.
WWJD for a Klondike Bar?
The primary reason this is so fasinating is not because of mass quanities, but because of the new possibility of manipulating bonds on molecules. This has many potential uses:
:)
1) Taking two reactants and manipulating certain bonds by hand may give more insight to why catylists work on similar reactions. Many catylists work without us knowing a great amount of detail on how they catylize a reaction. If certain bond manipulation cauese a reaction to proceed, it is likely that the catylist is weakening that bond--a clue to what is actually happening.
2) Intermediates. Some reactions (esp. in biochemistry) proceed without a good working knowledge of what intermediates form and what changes take place in getting to the intermediate (and so) onto allow the products to form.
3) Rare chemicals. There are some reactions that entropically / energetically make sense to occur, yet don't react because of other variables (such as bond tension--i.e. the formation of cyclo-pentane from larger molecules, etc...i know this is a baad example, can't think of something better). This gives us a method to try to understand and produce them, though not in bulk.
Besides, it's the Chemical Engineers responcability to do bulk production of anything anyway. Chemists just get to do the fun stuff and take all the credit. ChemE's are the ones that put it in the hands of John Doe.
(it's getting hot all the sudden...)
- Sig
1) Wait ten years
2) See how far off their predictions are
3) Go to step #1
1) Read shallow, badly-researched fluff pieces about a new technology
2) Don't bother trying to find anything to read by anyone who has a reasonable, knowledge-based point of view of the topic
3) Adopt oh-so-hip more-blase-and-cynical-than-thou attitude
4) Go to step #1
It was.