Deuteron spin lattice relaxation in amorphous ices

Abstract

Temperature-dependent deuteron spin lattice relaxation times T(1) have been obtained from water in its three amorphous states at ambient pressure: low density amorphous (LDA), high density amorphous (HDA), and very high density amorphous (VHDA). It is found that in all of these states the magnetization recovery is essentially monoexponential and that T(1) of LDA is significantly longer than that of the higher density forms. Thus, T(1) can be used as a monitor parameter to study the kinetics of the transitions from HDA to LDA and from VHDA to LDA. During the transformation of VHDA to LDA an intermediate state is formed, which, according to its T(1) at low temperature, is clearly determined to be HDA-like. However, and most significantly, the transition from VHDA to this HDA-like state and further on to LDA occurs at temperatures significantly above the kinetic stability limit of native HDA produced at 77 K. These findings contribute to the current discussion on the nature of HDA and VHDA by strengthening the view that the annealing of VHDA at ambient pressure produces a relaxed HDA-like state.