Temperature Measurement in Transmission Electron Microscope Using Cathodoluminescence of Whispering Gallery Mode

We demonstrate a novel in situ temperature measurement technique in a transmission electron microscope (TEM) using cathodoluminescence (CL) of optical whispering gallery modes (WGMs) in silicon spheres. This method allows for non-invasive, high-resolution thermal analysis under various stimuli such as electron beam irradiation and laser irradiation. The temperature was monitored by the WGM spectral peak shifts of Si spheres of 300–600 nm in diameter. Under continuous electron beam and laser irradiation, we observed steady-state temperature increases. In addition, the WGM spectral shifts under pulsed electron beams allowed us to investigate the temporal thermal responses through the monitored CL spectra. These results show that WGM-based CL thermometry enables precise local temperature measurement within the TEM, offering new capabilities for in situ studies as well as insights into electron beam effects.