In situ observation of fast surface dynamics during the vapor-deposition of a stable organic glass

E. Thoms, J. P. Gabriel, A. Guiseppi-Elie, M. D. Ediger, R. Richert

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

By measuring the increments of dielectric capacitance (ΔC) and dissipation (Δtan δ) during physical vapor deposition of a 110 nm film of a molecular glass former, we provide direct evidence of the mobile surface layer that is made responsible for the extraordinary properties of vapor deposited glasses. Depositing at a rate of 0.1 nm s-1 onto a substrate at Tdep = 75 K = 0.82Tg, we observe a 2.5 nm thick surface layer with an average relaxation time of 0.1 s, while the glass growing underneath has a high kinetic stability. The level of Δtan δ continues to decrease for thousands of seconds after terminating the deposition process, indicating a slow aging-like increase in packing density near the surface. At very low deposition temperatures, 32 and 42 K, the surface layer thicknesses and mobilities are reduced, as are the kinetic stabilities.

Original languageEnglish (US)
Pages (from-to)10860-10864
Number of pages5
JournalSoft Matter
Volume16
Issue number48
DOIs
StatePublished - Dec 28 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

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