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

Raman spectra of terephthalidenebis-p-n-decylaniline (TBDA) were recorded i n the regions 925-1000 and 1120-1220 cm(-1) from room temperature down to 2 0 K during both cooling and heating cycles. The subtle changes in the spect ral features of the bands at ca 975 and ea 1195 cm(-1) at 47 It were attrib uted to a hitherto unreported stable-metastable phase transition in TBDA, T he dynamics of the new phase transition are explained in terms of splitting of the non-planar mode at ca 975 cm-l due to strong steric hindrances caus ed by increased intermolecular interactions due to close packing in the low -temperature phase. Copyright (C) 1999 John Wiley & Sons, Ltd.