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

Abstract

The time evolution of the non-spin-flip $2\overline{A}\leftrightarrow \overline{E}$ spin-lattice relaxation in ruby has been studied with subnanosecond time resolution, following excitation of the broadband ${\mathrm{Cr}}^{3+}$ states with a ${\mathrm{N}}_2$ laser pumped-tunable-dye laser. From the short-time dependence of the $R_1$ and $R_2$ emission we directly obtain $T_1=1.1\mathrm{}$ ns for this relaxation. The branching ratio for relaxation from the broadband states to the $\overline{E}$ and $2\overline{A}$ states, respectively, is found to be 2.6. The significance of these measurements in relation to previous estimates of $T_1$ and to recent 29-${\mathrm{cm}}^{-1\mathrm{}}$ phonon spectroscopy is discussed.