Molecular Motion in ortho-Terphenyl

Abstract

Nuclear magnetic relaxation measurements have been made for ortho‐terphenyl in the liquid, crystalline, and glassy form. Self‐diffusion coefficients have been measured in the liquid. Molecular correlation frequencies derived from these measurements are shown to correlate well with published viscosity data. The results were found to be described satisfactorily by an equation of the form ${\nu }_c\mathrm{\hspace{0.17em}=\hspace{0.17em}A″}\exp {\mathrm{[-B\prime \hspace{0.17em}/\hspace{0.17em}(T-T}}_g\mathrm{)]}$ , but not by an equation of the form ${\nu }_c\mathrm{\hspace{0.17em}=\hspace{0.17em}A}\exp {\mathrm{(-\hspace{0.17em}C\hspace{0.17em}/\hspace{0.17em}TS}}_c)$ , where $S_c$ is the configurational entropy. Comments are made on the derivation of these functions and the nature of the molecular motions.