The glassy phase of 1-cyanoadamantane; a study of the molecular reorientations by high-resolution quasi-elastic neutron scattering

Abstract

Using the incoherent quasi-elastic neutron scattering (IQNS) technique, the motions of 1-cyanoadamantane C₁₀H₁₅CN are investigated below 170K in the glassy phase obtained by rapid quenching of the room-temperature orientationally disordered phase. The broadening of the experimental spectra is evidence for the existence of rotations of the molecules about their symmetry axes on the timescale 10^-11-10^-9 s. However, from a direct Fourier transform analysis, it is demonstrated that the experimental data cannot be described in terms of any simple jump model involving a single correlation time. In accordance with the conclusions of the studies by NMR and X-ray techniques, an interpretation based upon a distribution of the correlation times is proposed. Finally, the authors discuss whether this time distribution is a characteristic feature of this glassy state.