Relaxation of the Cr3+ion in emerald

Spin-lattice relaxation and cross relaxation have been studied for Cr 3+ ions in emerald over a concentration range of 0.49 × 10 20 to 1.75 × 10 20 ions cm -3 . Temperature dependence of T 1 was measured in the range 1.5-20 °K and orientation dependence from θ = 0 to 90°. Spin-lattice relaxation coupling rates have been calculated using the theory given by Van Vleck in 1940, the results being in fair agreement with experiment. The observed lengthening of T 1 at cross-relaxation points is explained in a simple manner. Cross-relaxation linewidths and rates have been measured for a 2:1 harmonic point near θ = 29°. Linewidths are in the region of 1000 Mc/s and maximum rates about 1000 sec -1 for Cr 3+ concentrations close to 0 5 × 10 20 ions cm -3 .