Molecular motions in compressed liquid heavy water at low temperatures

Journal Article · Wed Jun 15 04:00:00 EDT 1977 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.433901· OSTI ID:7313703

DeFries, T; Jonas, J

The NMR deuteron spin--lattice relaxation times T/sub 1/, self-diffusion coefficients D, and shear viscosities eta have been measured as a function of pressure in the temperature interval -15 to 10degreeC. The low-pressure extreme of the measurements is Ice I, whereas Ice V represents the high-pressure boundary of the experiments. In analogy with anomalous motional behavior in compressed liquid water, the initial compression of liquid D/sub 2/O in the temperature interval studied results in higher motional freedom of D/sub 2/O molecules so that T/sub 1/ and D dependences with pressure exhibit a maximum and shear viscosity shows a minimum. This is a result of distortion and weakening of the hydrogen bond network owing to compression. Further compression hinders molecular motions as a result of increased repulsive interactions due to higher packing. This study also enables us to test the applicability of hydrodynamic equations at the molecular level for liquid heavy water. Analysis of the relaxation and shear viscosity data show that the Debye equation fails to describe the density effects on reorientation of D/sub 2/O molecules. It appears that the success of the Debye equation to describe temperature effects on reorientation of H/sub 2/O and D/sub 2/O molecules at 1 bar is accidental. However, the data show that the deuteron relaxation rate (1/T/sub 1/)/sub D/ is proportional to eta/T under isochoric conditions. The fact that the slope of the (1/T/sub 1/)/sub D/ vs eta/T plot diminishes with increasing density indicates that compression leads to diminished coupling between rotational and translational motions of water molecules. The shear viscosity and self-diffusion data show that the Stokes--Einstein equation does not represent the relationship between D and eta in liquid heavy water. A brief discussion of the isotope effects on shear viscosity in liquid D/sub 2/O and H/sub 2/O is presented.

• Research Organization: Department of Chemistry, School of Chemical Sciences and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801
• OSTI ID: 7313703
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 66:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
COMPRESSIBILITY
DEUTERIUM
DIFFUSION
HEAVY WATER
HIGH PRESSURE
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MECHANICAL PROPERTIES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PRESSURE DEPENDENCE
RELAXATION
RESONANCE
SELF-DIFFUSION
STABLE ISOTOPES
VISCOSITY
WATER