Dipolar reorientations, metastability and orientational glass-like phase in α-CO

Abstract

The reorientational frequencies of the CO dipoles in the α-phase of carbon monoxide are derived from the temperature behavior of the ¹⁷O NQR linewidth and dielectric measurements. The extreme slowing-down of the reorientations and the orientational disorder in the “frozen” phase show up as a progressive broadening of the NOR line, over a few degrees, on cooling below 30 K. The occurrence of a metastable phase below 16 K is expected; analogies with orientational dipolar glasses are discussed.