Sub-millimetre Wave Spectra of Non-polar Liquids and Crystals

Abstract

IN a previous publication, the sub-millimetre wave spectra of polar liquids—and in particular chlorobenzene—were discussed¹. It was shown that in addition to the Debye absorption process at very low frequencies (<10 cm⁻¹) there existed a more intense absorption at frequencies characteristically in the range 20–100 cm⁻¹. This absorption, which was in the form of a very broad (half width ≈ 40 cm⁻¹) band with peak heights in the range 10–30 nepers/cm, was attributed to vibrational motion of the disordered lattice, that is, to “liquid lattice absorption”. Since then other work at the National Physical Laboratory and elsewhere (ref. 2 and Genzel, L., personal communication) has shown that absorption bands of this type are a general feature of the sub-millimetre wave spectra of polar liquids.