Nuclear Polarization in the B11(d,p)B12 Reaction. III

New measurements of the nuclear spin-lattice relaxation times of B12 implanted in Au, Pd, and Pt have established lower limits of 60, 185, and 270 sec A°K, respectively, of T1T for B12 in these metals. In conjunction with prior measurements of the effective moment of B12 in these metals, these T1T values show that the Knight shift of B12 in Au is positive, while in Pd and Pt it is negative. Using a common enhancement factor in these metals, one finds the value of the B12 magnetic dipole moment to be μ=(+1.002 85-0.000 14+0.000 15)μN. The B12 electric quadrupole moment has been measured for the first time using the asymmetry of the B12 resonance lines in Be foil under magnetic-field reversal and the estimated field gradient at Be9 lattice positions. The result is Q(B12)=(+0.030±0.008)×10-24 cm2.