Intersystem Crossing Rate and Triplet State Lifetime for a Lasing Dye

Abstract

Triplet state kinetics for rhodamine 6G in alcohol have been studied. The singlet‐to‐triplet intersystem crossing rate $k_{\mathrm{ST}}$ and triplet lifetime ${\tau }_T$ have been determined in air‐saturated alcohol, where the spin‐forbidden decay from the triplet manifold into the singlet ground state is enhanced by collision with oxygen molecules dissolved in the solution. Values of the kinetic parameters for air‐saturated ethanol solutions at room temperature were determined to be ${\tau }_T\text{\hspace{0.17em}=\hspace{0.17em}250\hspace{0.17em}±\hspace{0.17em}40}\mathrm{nsec}$ and $k_{\mathrm{ST}}{\text{\hspace{0.17em}=\hspace{0.17em}(3.4\hspace{0.17em}±\hspace{0.17em}1.3)\hspace{0.17em}×\hspace{0.17em}10}}^6{\sec }^{\text{−1}}$ .