Fig. 1: Versatile EEGS experiments using a continuous electron gun microscope.
a Schematics of the setup. A laser beam is focused down to a ~1 μm spot and positioned with sub-μm precision at Rf on the sample of interest by using a parabolic mirror. A monochromatized 200 keV electron is also focused on the sample and scanned to acquire EELS, EEGS, and CL signals. EEGS measurements are taken by synchronizing light (using a laser trigger) and electrons (through an e-beam blanker) at the detector. b A series of EELS spectra is acquired for a given electron probe position as the laser wavelength is scanned over the spectral region of interest (simulated data). The strength of the energy-gain signal is boosted when the light wavelength is close to an optical resonance of the specimen. c Schematic of a resonance probed by EEGS in a constant laser power regime. The energy-gain signal yields the EEGS intensity as a function of light wavelength, only limited by the nominal laser linewidth (7 μeV for the laser used in this study).
