A new phase transition in supercooled TBDA probed by low-temperature Raman study

Abstract

Raman spectra of terephthalidenebis-p-n-decylaniline (TBDA) were recorded in the regions 925-1000 and 1120-1220 cm-1 from room temperature down to 20 K during both cooling and heating cycles. The subtle changes in the spectral features of the bands at ca 975 and ca 1195 cm-1 at 47 K were attributed to a hitherto unreported stable-metastable phase transition in TBDA. The dynamics of the new phase transition are explained in terms of splitting of the non-planar mode at ca 975 cm-1 due to strong steric hindrances caused by increased intermolecular interactions due to close packing in the low-temperature phase. Copyright © 1999 John Wiley & Sons, Ltd.