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Nanoparticles Change Crystal Structure When Wet
Roland Piquepaille writes "This news release from the University of California at Berkeley is quite astonishing. 'A UC Berkeley team comprised of physicists, chemists and mineralogists reports on the unusual behavior of a semiconducting material, zinc sulphide (ZnS), when reduced to pieces only 3 nanometers across. They found that when the surface of a ZnS nanoparticle gets wet, its entire crystal structure rearranges to become more ordered, closer to the structure of a bulk piece of solid ZnS.' My summary includes two images of a 3 nanometer zinc sulphide (ZnS) nanoparticle with or without surface-bound water. How can this be used for? Surprisingly, they think that it 'could provide a way to tell whether pieces of rock from outer space came from planets with water.'"
Looks like it could be the same kind of process that triggers folding in organic chains in the presence of water ? After all, the water matrix does exert certain forces on particles that are at the same scale, it probably triggers an avalanche effect on the ZnS crystal starting at the surface of the material.
Surely with the multitude of molecules there would be some other that would cause such a re-arrangement.
To conclude that a space rock was formed in the presence of water could be an expensive mis-interpretation, such as if a space exploration program was based on that assumption.
I'm not trying to debunk their research but without experimenting with a wide variety molecules in different pressures and temperatures all that can be concluded is that "these crystals order themselves in water" not "any ordered crystal formed in water".
I look forward to finding out why I am wrong.
There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
The interaction of metal nanocrystals is a burgeoning field of science.
The presence of ligands (things like water, carbon monoxide, dinitrogen) can and does change the structure of metal clusters.
In these interactions both the geometric structure (the physical shape of the thing - what we see being altered here) and the electronic structure are important.
If for example the sum of the bond strength between a metal atom and say the hydrogen of water, and another metal atom with the ohter hydrogen of water is stronger than the bond between the two metal atoms, then the water molecule can push the two metal atoms apart and form a bridge between them.
The degree of change can be measured by spectrosopies such as UV/vis, IR, Raman etc. that allow characterisation of types & strength of bonds and forces.
Finding examples of this behaviour and learning how it can be directed by say changing the geometry of the metal cluster and by changing the ligand or the metal composition has applications in materials science, fabrication (using "dumb" molecules to direct the formation of certain crystal structures may be cheaper than forcing high pressures and so on).
Very exciting science!