The yellow shaded data are from a separate measurement cycle. The red shaded data point at 1.5 K
was obtained by equilibration of the triplet spin sublevel population via microwave irradiation (ODMR).
Download data file (Excel). View data.
The solid line in the above figure corresponds to the fit of the function in eq. 1 to the data between 39 and 200 K with.
kTG(T)=13.58
s-1 + 28.75 s-1exp(-501.5 K/T).
As in this temperature region the photoreaction renders only negligible
contributions to the triplet decay rate kT(T), the
data fit reflects the intramolecular acridine-d9 T1 decay
rate in the fluorene-d8D2 host crystal. Such a
weak temperature dependence is typical for intramolecular
decay rates in organic molecular crystals.