Interference distortion of the 73 cm−1 absorption line in polyethylene

The decrease of the absorption strength of the 73 cm−1 line in polyethylene and the strong antiresonance occuring above 310K at the high frequency side of the line are explained by assuming a Fano type coupling between the 73 cm−1 phonon and a continuum of infrared active vibrational modes. The parameters determining the line shape are deduced from experimental absorption curves and conceivable coupling mechanisms are discussed