Characteristic length of glass transition heterogeneity from calorimetry

The determination of the temperature fluctuation in a representative subsystem from experimental calorimetric curves is discussed. Contrary to the traditional fluctuation approach it is suggested to use the dispersion width of the corresponding relaxation spectrum and not the width of the peak in the imaginary part of the complex heat capacity as a measure of the temperature fluctuation in local subsystems. This leads to larger estimates for the length scales of the dynamic heterogeneity of the dynamic glass transition than originally supposed. A correction method for former results is given and the comparison with other experimental results is discussed.