We report the thermodynamic measurement of the enthalpy released during the aging of supported films of a molecular glass former, toluene, at temperatures well below the glass transition temperature. By using microfabricated devices with very short equilibration times (below 1s), we evidence a remarkable variation of the relaxation rate on decreasing film thickness from 100nm down to a 7nm thick film. Our results demonstrate that surface atoms are more efficient than bulk atoms in attaining low energy configurations within the potential energy landscape. © 2011 American Physical Society.
|Journal||Physical Review Letters|
|Publication status||Published - 7 Jul 2011|