Brillouin scattering study of liquid–glass transitions of aminopropanols

An angular dispersion-type Fabry–Perot interferometer (ADFPI) was used to measure the Brillouin spectra of aminopropanols with different chemical structures. A high reflectivity and flatness of solid etalon and a highly sensitive charge-coupled device (CCD) detector were employed to obtain a high finesse above 100 in the short acquisition time. The glass-forming tendency and behavior of velocity and width of Brillouin spectra of aminopropanols were affected by the structure of molecules. The glass transitions were observed in 1-amino-2-propanol and 2-amino-1-propanol, while crystallization occurred in pure enantiomer of l-isomer 1-amino-2-propanol and 3-amino-1-propanol on cooling. It is found that the tendency of vitrification is different between racemic liquid and its pure enantiomer in cooling rate range from 2 to 4 K/min. The relaxation time was calculated by the simple viscoelastic theory using the data of sound velocity. It obeys the Arrhenius law in the sufficiently high temperature range.