研究目的

Investigating the dynamical processes in supercooled AsSe9 liquid using 1D and 2D 77Se NMR spectroscopic techniques to understand the coexistence of two distinct dynamical processes and their coupling to viscosity.

研究成果

The study reveals the coexistence of two distinct dynamical processes in AsSe9 liquid: a slow process related to chemical exchange between Se environments and a fast process related to Se chain segmental motion. The slow process is closely coupled to viscosity over the entire temperature range, while the fast process becomes coupled to viscosity only near the glass transition. The activation energy of the slow process is consistent with Se-Se/As bond energies, whereas the fast process shows a significantly higher activation energy, indicative of its cooperative nature.

研究不足

The study is limited to the AsSe9 composition and the temperature range near its glass transition. The precise estimation of timescales for the fast process from 2D EXSY spectra is challenging due to the lack of constraints on the relative broadening effects of the static line shapes.