Low-frequency Raman-active modes and temperature dependences in oligo-oxyethylene

Raman spectra have been recorded for monodisperse and polydisperse samples of oligooxyethylene at several temperatures in the range 310–77 K. Four scattering peaks are found with frequency dependent on temperature. One at 92–80 cm^?1 is unaffected by changes in chain length and is assigned to a lattice mode. The others are chain-length dependent and are assigned either to the longitudinal acoustical modes (LAM-1 and LAM-3)or, less certainly, to a transverse acoustical mode.