Investigation of low-temperature line broadening mechanisms in organic amorphous solids with photon echo, hole-burning and single-molecule spectroscopy

We present the first comparative analysis of spectral data obtained at low temperatures with three different highly selective techniques: two-pulse photon echo (2PE), hole-burning (HB) and single-molecule spectroscopy (SMS) of a polyisobutylene glass (PIB) doped with tetra-tert-butylterrylene (TBT). Our 2PE- and HB-experiments are compared with literature data [Tittel et al., J. Lumin. 64 (1995) 1] obtained by SMS. It is found that the linewidth measured by HB is significantly larger than the mean of the linewidth distribution obtained by SMS. We conclude that a T2-dispersion plays an important role in the formation of the linewidth dispersion in TBT/PIB.