Symmetrized Normal Mode Analysis of the Spin-Lattice Relaxation in Solid Calcium Borohydride

摘要

The symmetrized normal mode analysis presented in a previous paper was used to analyze the ~(11)B spin-lattice relaxation of solid calcium borohydride.From the analytical results,the quadrupolar and the dipolar spectral densities and reorientational correlation times of various relaxation interactions were evaluated.Based on the spectral densities,the quadrupolar contribution to the spin-lattice relaxation of ~(11)B nucleus was calculated.As expected from the QCC value of ~(11)B nucleus in solid calcium borohydride,the ratio of the quadrupolar contribution to the dipole-dipole contribution in the ~(11)B spin-lattice relaxation was proved to be higher than 30% at 100°C.The symmetrized normal mode could be a useful method for the interpretation of AX4 spin system containing a quadrupolar nucleus,and thus the determination of the motional parameters of BH4 unit in solid calcium borohydride.