Showing papers by "Edward T. Samulski published in 1972"
TL;DR: In this article, an experimental study of proton, deuteron, and nitrogen resonance of dimethylformamide and deuterated DMF has been made in oriented nematic liquid crystals of polyglutamic acid.
Abstract: An experimental study of proton, deuteron, and nitrogen resonance of dimethylformamide and deuterated DMF has been made in oriented nematic liquid crystals of poly‐L‐glutamic acid. The solvents used were various mixtures of DMF and H2O or D2O. From the proton spectra the complete order matrices were determined for each solvent system. From consistency between the solvent systems the angle HCN of the amide could be determined and was found to be 107± 1°. From the observed quadrupole splittings of all deuterium nuclei and of nitrogen in (deuterated) DMF in three solvent systems, all elements of the quadrupole coupling tensors of these nuclei were obtained. The quadrupole coupling constants and asymmetry factors found were: for the amide deuteron 197 kHz, 0.13; for the methyl deuterons trans to the amide oxygen 46 kHz, 0.19 and for those cis to the amide oxygen 64 kHz, 0.06 (averaged over methyl rotation); for the nitrogen 3.3 MHz, 0.4. Deuteron quadrupole splitting of solvent water was also observed, while ...
35 citations
TL;DR: In this paper, the relative importance of intermolecular and intramolecular contributions to nuclear spin relaxation in liquid crystals is discussed with particular emphasis on p-azoxyanisole (PAA).
Abstract: The relative importance of intermolecular (T lr) and intramolecular (T la contributions to nuclear spin relaxation in liquid crystals is discussed with particular emphasis on p-azoxyanisole (PAA). Previously published data on T lr and T la in PAA, obtained by isotopic dilution studies, are reinterpreted in view of recent advances. Derived correlation times for rotation and translation at 120°C (nematic phase) and at 136°C (isotropic phase) calculated for different mechanisms are compared.
20 citations
TL;DR: In this paper, a modification of the Varian HA•100 NMR spectrometer to permit frequency sweep adiabatic fast passage measurements of T1 is described, which can be operated in the lock mode making signal averaging possible.
Abstract: A modification of the Varian HA‐100 NMR spectrometer to permit frequency sweep adiabatic fast passage measurements of T1 is described. The spectrometer can be operated in the lock mode making signal averaging possible.
4 citations