Time-resolved spectroscopic study of the excited-state spin-phonon interaction in ruby

The time evolution of the non-spin-flip 2Ā↔Ē spin-lattice relaxation in ruby has been studied with subnanosecond time resolution, following excitation of the broadband Cr³⁺ states with a N₂ laser pumped-tunable-dye laser. From the short-time dependence of the R₁ and R₂ emission we directly obtain T₁=1.1 ns for this relaxation. The branching ratio for relaxation from the broadband states to the Ē and 2Ā states, respectively, is found to be 2.6. The significance of these measurements in relation to previous estimates of T₁ and to recent 29-cm^-1 phonon spectroscopy is discussed.