Complete temperature dependence of the far infrared absorption spectrum of linear polyethylene from 14°k to the melting point

In the far infrared, polyethylene shows two absorption bands: a very strong one at 73 cm−1 and a weak one centered at 109 cm−1 which is only observable below 160°K. From the frequency and temperature dependence of the 73 cm−1 band, the maximum frequency shift, the peak height, integrated absorption intensities, and the integral half-width are determined. The frequency shift with temperature is shown to be a linear function of the related lattice parameter. A comparison with the temperature behavior of the CH2-rocking vibration at 730 cm−1 is given.