The Surface Mobility of Glasses

Surface diffusion on frozen polymer glasses is influenced by the surface dynamics of the glass itself. [Also see Report by Chai et al.] The diffusion of atoms and molecules on a crystal surface plays an important role in myriad applications including thin-film deposition, sintering, and heterogeneous catalysis (1, 2). Surface diffusion is frequently observed at temperatures appreciably below the crystal's melting point, implying a role for enhanced surface mobility in the process. However, understanding the dynamics of surface diffusion in glasses is a research area still in its infancy. On page 994 of this issue, Chai et al. (3) present an experimental technique that enables detailed quantification of the near-surface mobility of glasses.