Effect of ${\mathrm{Al}}^{27}$ on Electron Cross Relaxation in Ruby

Nonexponential electron-spin cross relaxation in dilute ruby provides a measure of the coupling between the ${\mathrm{Cr}}^{3+}$ electron dipole—dipole reservoir and the aluminum nuclear Zeeman reservoir. The electron dipole—dipole reservoir is more closely coupled to the nuclei than to the remainder of the electron-spin system. A relation is obtained between electron spin-lattice relaxation and nuclear spin-lattice relaxation in ruby.