Inelastic neutron scattering study of the glass former ZnCl2

Triple-axis neutron scattering measurements on ZnCl2 glass are described. The inelastic scattering S(Q, ω) for constant Q scans shows a pronounced low-frequency excitation feature in the region 0.2 to 0.7 THz in the glassy and supercooled liquid states, which can be identified with the boson peak that has been observed in other systems. Detailed results show that this feature has the temperature dependence of harmonic vibrations, in particular its frequency is independent of the temperature. Further it shows no dispersion in Q, and the intensity is strongly correlated with the static structure factor S(Q).