文摘
We investigate the temporal dynamics of terrylene diimide molecule with four phenoxy rings (TDI) in a poly(styrene) (PS) matrix in the supercooled regime by use of single molecule spectroscopy. By recording both fluorescence lifetime and linear dichroism observables simultaneously, we show that the TDI dye molecule is a versatile probe of the local dynamics in the polymer. The molecule is able to undergo conformational changes, as indicated by lifetime fluctuations and/or reorientation jumps, as indicated by both observables on different time scales. Owing to molecular mechanics and quantum calculations, we could assign the conformational changes to folding/unfolding event(s) of one or more arms with respect to the conjugated core. We tentatively attribute the different spatial extents of the locally probed motions to the α and β relaxation processes occurring in the PS matrix.