Published in Physical Review Letters, Volume 106, Issue 23, June 10, 2011, pages 1-4.
NOTE: At the time of publication, the author Gregory Scott was not yet affiliated with Cal Poly.
The definitive version is available at https://doi.org/10.1103/PhysRevLett.106.235501.
Amorphous silicon is an important material, amidst a debate whether or not it is a glass. We produce amorphous Si surfaces by ion bombardment and vapor growth, and image discrete Si clusters which hop by two-state dynamics at 295 K. Independent of surface preparation, these clusters have an average diameter of ~5 atoms. Given prior results for metallic glasses, we suggest that this cluster size is a universal feature. The hopping activation free energy of 0.93 ± 0.15 eV is rather small, in agreement with a previously untested surface glass model. Hydrogenation quenches the two-state dynamics, apparently by increasing surface crystallinity.
Biochemistry | Chemistry
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