Details

Autor(en) / Beteiligte

• Micko, B
• Kruk, D
• Rössler, E A

Titel

Primary and secondary relaxation process in plastically crystalline cyanocyclohexane studied by 2H nuclear magnetic resonance. II. Quantitative analysis

Ist Teil von

• The Journal of chemical physics, 2013-02, Vol.138 (7), p.074504-074504

Ort / Verlag

United States

Erscheinungsjahr

2013

Quelle

AIP Journals Complete

Beschreibungen/Notizen

• We analyze the results of our previously reported 2H nuclear magnetic resonance (NMR) experiments in the plastically crystalline (PC) phase of cyanocyclohexane (Part I of this work) to study the fast secondary relaxation (or β-process) in detail. Both, the occurrence of an additional minimum in the spin-lattice relaxation T1 and the pronounced effects arising in the solid-echo spectrum above the glass transition temperature T(g) = 134 K, allow for a direct determination of the restricting geometry of the β-process in terms of the "wobbling-in-a-cone" model. Whereas at temperatures below T(g) the reorientation is confined to rather small solid angles (below 10°), the spatial restriction decreases strongly with temperature above T(g), i.e., the distribution of cone angles shifts continuously towards higher values. The β-process in the PC phase of cyanocyclohexane proceeds via the same mechanism as found in structural glass formers. This is substantiated by demonstrating the very similar behavior (for T < T(g)) of spin-lattice relaxation, stimulated echo decays, and spectral parameters when plotted as a function of <log τ(β)> (taken from dielectric spectroscopy). We do, however, not observe a clear-cut relation between the relaxation strength of the β-process observed by NMR (calculated within the wobbling-in-a-cone model) and dielectric spectroscopy.