The effect of spectral diffusion on the phase coherence of phosphorescent triplet spins

We have made a systematic study of the effect of spectral diffusion on the phase coherence of phosphorescent triplet spins. The effect is caused by time dependent hyperfine interactions with surrounding nuclear spins, which make the resonance frequencies of the spin-packets vary in time. From the behaviour of the spin echo signals we derive characteristic parameters for these frequency instabilities.