Using picosecond laser pulse techniques, we have studied how increasing temperature leads the finite-system equivalent of melting in cesium-iodide particles containing only 7 atoms and a pair of unattached electrons. These particles have three basic shapes: cube, ladder, and ring:
At temperatures only slightly above room temperature, these particles transform rapidly between those three forms.
While our studies are experimental in nature, we have also implemented molecular dynamics simulations to help us understand what we observe in the actual measurements. Click here:
(Real Media Format)
(Windows Media Format)
to watch a movie of these isomerizations taking place in real time over a 500 picosecond period . For ease of calculation, the simulations show (CsI)4 clusters rather than the (CsI)3Cs- clusters that we actually observe experimentally. Thus the pair of electrons (which are not visible in the drawings above) are replaced in the movie by an extra iodide ion.