Solvation dynamics in supercooled liquids: the quinoxaline triplet stae in 2-MTHF at the glass transition

Abstract

The phosphorescence of quinoxaline as dopant in 2-MTHF is investigated at temperatures near the glass transition of the host solution. Within the accessed time range from 500 μs to 1 s, the emission band is subject to a temporally resolved Stokes shift of ≈ 250 cm −1 monitoring the solvation dynamics of the excited probe molecule. The non-exponential Stokes-shift correlation functions indicate that microscopic aspects of the solvation process have to be considered for rationalizing the experimental data. The results are discussed in the context of solvations dynamics of singlet excitations and the dielectric behaviour of supercooled liquids.