Reorientation of D2O in concentrated aqueous solutions of lithium chloride studied by nuclear magnetic relaxation
- 1 January 1978
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
- Vol. 74, 353-366
- https://doi.org/10.1039/f29787400353
Abstract
Deuteron spin–lattice T1 and spin–spin T2 relaxation times have been measured at 10 MHz in aqueous (D2O) solutions of lithium chloride as a function of concentration (R= 3.5 to 6.3 mol D2O per mol LiCl) and temperature (175–320 K). These measurements are analysed using an empirical Cole–Davidson distribution of reorientational correlation times τ2 for D2O. The mean values of τ2 are found to be represented by 2=(1.24 ± 0.27)× 10–13 s exp {(701 ± 21) K/(T–T0)} with T0 values of 137 K (R= 3.7), 129 K (R= 4.8) and 125 K (R= 6.3). At low temperatures, the 2 are similar to the corresponding shear relaxation times s, measured between 149–173 K, while at 298 K, 2, the dielectric relaxation time D and the neutron diffusional correlation time τ0 have similar values. It is, therefore, concluded that the reorientation of the D2O molecules in these solutions is governed by the structural fluctuations associated with the glass transition. T1 measurements at 298 K, in the range R= 3 to 10, are interpreted to show that these solutions have similar structures to the corresponding glasses at 100 K : small clusters of Li+(H2O)4Cl– with excess water incorporated interstitially and having dynamic properties remarkably similar to those of bulk water. Previous T1 measurements for water (D2O) are reanalysed and the 2 shown to be dominated by a thermodynamic singularity at Ts= 228 K.Keywords
This publication has 0 references indexed in Scilit: