Heterogeneous relaxation patterns in supercooled liquids studied by solvation dynamics

We have measured the solvation dynamics of a dipolar supercooled liquid near its glass transition in a temperature range in which the average structural relaxation time varies more than four orders of magnitude. The analysis of the time dependent average emission energy and the inhomogeneous linewidth of the [Formula Presented] transition reveals that the orientation correlation decay pattern intrinsic in each relaxing unit is associated with a stretching exponent [Formula Presented] in the entire range [Formula Presented] Our analysis also allows one to detect fluctuations in terms of the resulting apparent homogeneity within the long time tail of the decay. Even at times significantly exceeding the average structural relaxation time, no sign of a transition towards purely exponential or otherwise homogeneous behavior could be observed. This implies that even at [Formula Presented] the individual time constants remain correlated to their initial values at [Formula Presented]