In-Situ Thermal Mapping of Graphene via TEM Measurement of the Debye-Waller Factor

Thermal motion of the constituent atoms attenuates high-order peaks in a crystal's electron diffraction pattern. Using TEM we measure this attenuation, parameterized by a Debye-Waller factor, in single-layer cleaved graphene that is Joule-heated \emph{in situ}. We find that the Debye-Waller factor, as probed with selected area electron diffraction, provides a reliable measure of the local temperature and thus allows for quantitative thermal mapping on the nanoscale.