NUCLEAR SPIN RELAXATION IN BERYLLIUM METAL

The quadrupole-split NMR spectrum of Be9 nuclei (I = 3 2) in pure Be metal has been studied by pulse methods. The free induction decay (FID) is modulated: the frequency of modulation gives a new measurement of the quadrupole coupling constant e2qQ h = 57 ± 1 kHz. Analysis of the FID shows also that the central line and satellites are non-gaussian. Their second moments agree with the dipolar values in an annealed sample. If the sample is not annealed the satellites are broadened. The width of the distribution of the electric field gradient has been deduced. The spin echo envelope is also modulated. Previous calculations of echoes in quadrupole-split systems are verified for this particular case. Spin lattice relaxation time T1, measurements show that T1T is constant from 1.5 to 300°K. The value of this constant depends of the state of annealing of the sample. This observation shows that the electronic structure of Be is very sensitive to slight changes of the crystal structure. After a long anneal T1T= (1·85 ±0·10) × 104sec °K. © 1968.