Boltzmann-Distribution-Driven\nCathodoluminescence\nThermometry in <i>In Situ</i> Transmission Electron Microscopy

Nanothermometry in <i>in situ</i> transmission\nelectron\nmicroscopy (TEM) is useful for comprehending the functioning mechanisms\nof the heterogeneous matter through real-time observations. Herein,\nwe introduce a Boltzmann-distribution-driven cathodoluminescence (CL)\nnanothermometry for <i>in situ</i> local temperature probing\nin TEM. The population distribution across the close-lying Stark sublevels\nof dysprosium ions in an yttrium vanadate matrix follows the Boltzmann\ndistribution, enabling the use of the CL-intensity ratio as a thermometry\nover a wide temperature range of 103–435 K with a relative\nsensitivity exceeding 3% K<sup>–1</sup> and precision of ±2%.\nSuperior to other CL-based thermometries, the present approach is\nindependent of electron–beam parameters and dopant concentration,\nextending the robustness and applicability of CL-based nanothermometry\nin electron microscopy. We further demonstrate the real-time mapping\nof the temperature distribution across a TEM grid under laser irradiation.