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Mechanical hole burning spectroscopy: evidence for heterogeneous dynamics in polymer systems.

We have developed a mechanical spectral hole burning (MSHB) scheme that is analogous to nonresonant dielectric spectral hole burning (DSHB). DSHB experiments have been performed close to the glass temperature and interpreted in terms of dynamic heterogeneity. Here we find that holes are burned far above the glass temperature and in the terminal regimes for a branched polymer melt and a polymer solution. The results suggest that MSHB is a potentially powerful tool with which to examine dynamics of complex fluids.