Spin-echo Decay Rate Research Articles

On the relationship between transient and CW NMR experiments in dilute magnetic alloys

The enhancement of experimental nuclear magnetic relaxation rates resulting from strong quadrupolar broadening of the resonance is discussed for both transient (spin-echo) and steady-state (CW) techniques. Contrary to recent claims it is shown that the enhancements of the spin-echo decay rate and homogeneous linewidth are identical.

The determination of all six spectral densities of motion for partially oriented dichloromethane- d2

Measurements of spin-lattice relaxation, combined with 2D measurements of single- and double-quantum spin-echo decay rates, have been used to determine the complete set of spectral density parameters which characterize deuterium relaxation of CD 2Cl 2 partially oriented in a nematic liquid crystal (Merck Licristal Phase V). At 31.5°C and 9.2 MHz, terms describing cross-correlation between two deuterium quadrupole coupling tensors are found to be comparable to the autocorrelation terms. A partial interpretation of these results in terms of anisotropic molecular reorientation and order-director fluctuations is presented and is confirmed by additional measurements of the temperature and field dependence of spin-lattice relaxation rates.

Nuclear Magnetic Resonance Study of the Protolysis of Trimethylammonium Ion in Aqueous Solution—Order of the Reaction with Respect to Solvent

It was found previously that the proton-transfer reaction between trimethylammonium ion and trimethylamine in aqueous solution takes place via water. In the present investigation the number of water molecules involved in this reaction was determined. Proton exchange rates were determined from NMR measurements in trimethylamine—trimethylammonium chloride buffer solutions in O17-enriched water. It is concluded that one water molecule is involved in the transfer reaction. In the appendix, theoretical equations are derived for the dependence of the observed spin-echo decay rate on the 180° pulse rate for the case of fast exchange.