CO/N2 solid solutions: Head–tail reorientations

Abstract

The rates of CO reorientation in α-phase solid solutions of CO/N2 were determined with dielectric spectroscopy. The activation energy is found to be an increasing and approximately linear function of the CO concentration x, similar to the transition temperature Tαβ. The extrapolated activation energy for CO reorientation in α-N2 is compared to that in pure α-CO; the transition temperatures and libration frequencies of α-N2 and α-CO are also compared. Evidently, the same interactions control Tαβ, the librations, and the energy barriers to reorientation. The CO dipole moment magnitudes determined from the dielectric data are all about 30% below the free molecule value. Not all of this discrepancy is ascribable to incomplete filling of the cell by the solid sample and librational reduction of the effective moment.