Spectroscopic study of the encaged molecule motion in some clathrates

The far infra-red spectra of seven different gases trapped in the cages of β-quinol clathrates have been studied. Data are provided for N2, CO2, CO, HCl, HBr, SO2 and HCN in the frequency range 10–100 cm–1. For the chosen systems it has been possible to indicate (i) the degree to which quantization of the rotational states is maintained by polar guests in the clathrate and what displacement can be seen relative to free gas molecules, (ii) some factors governing the translational (“rattling”) mode of the guest molecule. The frequencies and relative intensities of quantized rotation, hindered rotation and “rattling” mode absorptions have been studied over a temperature range 4.2–300 K.