Measuring three-dimensional orientational motions of many individual molecules within glassy state poly(methyl methacrylate) has enabled nanoscopic probing of bulk-obscured polymer dynamics. Complementing bulk studies, the measured distributions of nanoscale barriers to rotational motion afforded by our single molecule orientational methods directly probe the spatial heterogeneity and nanoscopic $\alpha$-relaxation dynamics deep within the glassy state.

• Received 8 July 2001

DOI:https://doi.org/10.1103/PhysRevLett.89.026101