Nuclear spin-lattice and nuclear spin-spin relaxation time measurements in EuB6 at low temperatures using the spin-echo technique

Experimental results on the nuclear spin-lattice and nuclear spin-spin relaxation times in the ferromagnetic EuB₆ at temperatures below 4·2 K are presented using the external magnetic field,H _ext, in the range of 0 ⩽H _ext ⩽ 10 kG. Nuclear spin-spin relaxation time computed on the basis of the Suhl-Nakamura process turns out to be 3·2μs, which compares well with the experimental value 11·1μs obtained with the 10 kG magnetic field at 1·7 K. It is found that in the ferromagnetic EuB₆,T ₁ is approximately 5 × 10³ times larger thanT ₂ at 1·7 K with the 10 kG magnetic field. Thus the effect ofT ₁ onT ₂ can be neglected. From the experimental value ofT ₂, the value of the homogeneous line broadening is found to be 14 kHz. The corresponding value obtained from the cw method is 175 kHz. This evidently shows the presence of the inhomogeneous line broadening in the cw NMR.     

Carbon networks based on dehydrobenzoannulenes. 3. Synthesis of graphyne substructures

This Letter describes the synthesis of the first macrobicyclic subunits of the hypothetical all-carbon network graphyne. Key to synthetic success is an intramolecular Sonogashira cross-coupling sequence.     

A Guide to Medical Computing (Computers in Medicine Series)

Journal of the Operational Research Society -     

Iron Mössbauer spectra of lava from Jeju island and its similarities to Moon basalts

We report the result of measurements of the⁵⁷Fe Mössbauer spectrum for powder samples of lava taken from four widely separated sites on Jeju island. The spectra consist of well defined quadrupole doublets having a 2+ charge state and indicate the presence of olivine, clinopyroxene, and ilmenite. In addition we find a six line magnetically split hyperfine pattern characteristic of impure hematite, with considerable line broadening and reduced internal field. The observed spectra have a remarkable similarity to those found for moon basalts. A recently popularized “collision ejection” model for the moon formation would be consistent with our observations. The data is a particularly simple and direct illustration of the well-known fact that the iron silicates and ilmenite found on the moon are very similar in composition and relative abundance to that found on earth.