The temperature dependence of the characteristic length for the dynamic glass transition in ortho-terphenyl is determined, for the first time, from combined results of depolarized dynamic light scattering, photon correlation spectroscopy, and viscosity experiments. The length is found to vary according to ${\xi }_{\mathit{a}}$∼(T-${\mathit{T}}_{\mathrm{\infty }}$${)}^{\mathrm{-}\nu }$ where ${\mathit{T}}_{\mathrm{\infty }}$ is the Vogel temperature, with an exponent ν-0.69±0.06 in the temperatur region from up ${\mathit{T}}_{\mathit{g}}$ up to ${\mathit{T}}_{\mathit{g}}$+80 K.

• Received 30 December 1991

DOI:https://doi.org/10.1103/PhysRevLett.68.2344