Imaging the Sublimation Dynamics of Colloidal Crystallites
J. R. Savage,1
D. W. Blair,1
A. J. Levine,2
R. A. Guyer,1
A. D. Dinsmore1
We studied the kinetics of sublimating crystals with single-particle
resolution by experiments with colloidal spheres and by computer
simulations. A short-range attraction between spheres led to
crystallites one to three layers thick. The spheres were tracked
with optical microscopy while the attraction was reduced and
the crystals sublimated. Large crystallites sublimated by escape
of particles from the perimeter. The rate of shrinkage was greatly
enhanced, however, when the size decreased to less than 20 to
50 particles, depending on the location in the phase diagram.
At this size, the crystallites transformed into a dense amorphous
structure, which rapidly vaporized. The enhancement of kinetics
by metastable or unstable phases may play a major role in the
melting, freezing, and annealing of crystals.
2 Department of Chemistry and Biochemistry and California Nanosystems Institute, University of California, Los Angeles, CA 90095, USA.
