Molecular Motion in Solid HCl and DCl. Quadrupole Coupling in the Low-Temperature Phase

Abstract

The 35Cl pure quadrupole spectra of HCl and DCl have been examined by pulse techniques between 50°K and the phase transformations at 98.36° and 105.03°K. In these materials, T1 is shorter than about 400 μsec above about 63° and 77°K, respectively, but shows behavior typical of a thermally activated rate process at lower temperatures. Activation energies for both compounds are 2.70±0.05 kcal/mole, in good agreement with values obtained from dielectric constant data. In HCl, T2, probably determined by the proton moment, is of the order of two to three times T2*, while in DCl T2 is 40 to 50 times T2* in the temperature range for which it is not controled by T1. The data are discussed in terms of possible molecular motions in the solids in the low-temperature phase.