Neutron scattering studies of solid-state polymorphism in dimethyl butanol glass formers

Inelastic incoherent neutron scattering (IINS) and neutron powder diffraction (NPD) studies have been performed for two dimethyl 1-butanols and two dimethyl 2-butanols with CH3 side molecular groups. Low-temperature vibrational density of states confirmed solid-state polymorphism detected by calorimetric methods, i.e., existence of crystalline and ODIC phases for all isomers, orientationally disordered glass for 2,2-DM 1-B and 3,3-DM 2-B, and glass of isotropic phase for 3,3-DM 1-B. Difference in vibrational density of states between glass and the ordered crystal has shown the so-called Boson peak. Influence of the OH group position in the molecules on their vibrational dynamics up to 50 meV is discussed.