A. Loewenstein

Nuclear magnetic relaxation in liquid ammonia and conditional inertial rotation in liquids

A theory of nuclear magnetic relaxation induced by inertial rotation in polar liquids is described. It is proposed that such rotation occurs only when the neighbourhood of a molecule attains an expanded lattice configuration. The non-markovian processes involved in the relaxation are expressed in terms of rate constants that occur in a formulation due to Anderson, and these are interpreted in terms of the unconditioned inertial rotation theory described in the preceding paper. The theory is used to interpret the values of T 1 obtained for 14N and D in liquid ammonia. The paper concludes with an outline of a general theory of anisotropic diffusion in liquids.

Proton and deuteron magnetic resonance of methanes, silanes and GeH3D dissolved in nematic liquid crystals

The proton and deuteron magnetic resonance spectra of CH4, CH3D, CH2D2, CHD3, CD4, SiH4, SiH3D, SiH2D2, SiH3D, SiD4, GeH3D, dissolved in nematic liquid crystals, are reported. It was found that these molecules, which are essentially tetrahedral, exhibit anisotropic interactions and are partially oriented in the nematic phase. This effect is presumably due to slight deformations induced by the anisotropic medium. Some of the aspects related to the interpretation of the results are discussed.

Deuterium relaxation in C6D6 dissolved in a liquid crystal

Relaxation times, T 1 and T 2, of deuterium in C6D6 dissolved in the nematic phase of 4,4′-n-hexyloxyazoxybenzene at 75·3°c are reported. Relaxation times were calculated in terms of a correlation time τc using the Redfield theory adapted for a partially ordered molecule. Values of τc derived from T 1 and T 2 are similar.

Nuclear magnetic resonance isotope chemical shifts in BH4 -, CH4 and NH4 +

The 11B and 14N chemical shifts in deuterium substituted XH4 (X=B, N) are reported. Both shifts are to high magnetic fields. The low field shift of the protons in deuterated NH4 + has been re-measured under conditions that suggest that it is not due to interaction with the solvent as was proposed previously. A model, based on electric field considerations is presented which is capable of explaining the low field proton shifts in deuterated NH4 + as compared to the high field shifts in deuterated BH4 - or CH4. The effect is related to the higher electronegativity of N as compared to B or C.