Measurement of the intersystem crossing rate in aluminum tris(8-hydroxyquinoline) and its modulation by an applied magnetic field

The rate constant for intersystem crossing in aluminum tris(8-hydroxyquinoline) was measured using the time dependence of the luminescence under high excitation intensity and modeling using a rate equation approach. Under high illumination levels intersystem crossing results in the transfer of singlets into triplets, which due to their long lifetime effectively remove molecules from participating in photoluminescence. The intersystem crossing rate was found to be ∼2.2×104 s−1 at 80 K. The presence of a magnetic field was found to increase the rate constant by ∼10% with applied fields of ∼100 mT.